diff --git a/Changes b/Changes
index 2bfc523..cc49dee 100644
--- a/Changes
+++ b/Changes
@@ -7,6 +7,8 @@
         - [feature] Presorting of element terms in the index for coherent
 	  SpanQuery sorting; Removed buffering of element candidates (diewald)
 	  Warning: This is a breaking change!
+	- [feature] Added CorpusDataException to deal with data importing bugs;
+          made some imports break more easily though (diewald)
 	- [performance] Payloads in ElementSpans can now be lazily loaded,
 	  MatchModifyClassSpans no longer rely on payload copies (diewald)
 	- [cleanup] Renamed /filter to /collection, 
diff --git a/src/main/java/de/ids_mannheim/korap/index/FieldDocument.java b/src/main/java/de/ids_mannheim/korap/index/FieldDocument.java
index c0815ec..8a643eb 100644
--- a/src/main/java/de/ids_mannheim/korap/index/FieldDocument.java
+++ b/src/main/java/de/ids_mannheim/korap/index/FieldDocument.java
@@ -5,6 +5,7 @@
 import de.ids_mannheim.korap.model.MultiTermToken;
 import de.ids_mannheim.korap.KorapDocument;
 import de.ids_mannheim.korap.util.KorapDate;
+import de.ids_mannheim.korap.util.CorpusDataException;
 
 import com.fasterxml.jackson.annotation.*;
 import com.fasterxml.jackson.databind.ObjectMapper;
@@ -135,16 +136,22 @@
         // Iterate over all tokens in stream
         for (ArrayList<String> token : (ArrayList<ArrayList<String>>) node.get("stream")) {
 
-            // Initialize MultiTermToken
-            MultiTermToken mtt = new MultiTermToken(token.remove(0));
+            try {
+                // Initialize MultiTermToken
+                MultiTermToken mtt = new MultiTermToken(token.remove(0));
 
-            // Add rest of the list
-            for (String term : token) {
-                mtt.add(term);
+                // Add rest of the list
+                for (String term : token) {
+                    mtt.add(term);
+                 };
+
+                // Add MultiTermToken to stream
+                mtts.addMultiTermToken(mtt);
+
+            }
+            catch (CorpusDataException cde) {
+                this.addError(cde.getErrorCode(), cde.getMessage());
             };
-
-            // Add MultiTermToken to stream
-            mtts.addMultiTermToken(mtt);
         };
 
         // Add tokenstream to fielddocument
@@ -178,13 +185,18 @@
 
             for (ArrayList<String> token : (ArrayList<ArrayList<String>>) field.get("data")) {
 
-                MultiTermToken mtt = new MultiTermToken(token.remove(0));
+                try {
+                    MultiTermToken mtt = new MultiTermToken(token.remove(0));
 
-                for (String term : token) {
-                    mtt.add(term);
+                    for (String term : token) {
+                        mtt.add(term);
+                    };
+
+                    mtts.addMultiTermToken(mtt);
+                }
+                catch (CorpusDataException cde) {
+                    this.addError(cde.getErrorCode(), cde.getMessage());
                 };
-
-                mtts.addMultiTermToken(mtt);
             };
 
             // TODO: This is normally dependend to the tokenization!
diff --git a/src/main/java/de/ids_mannheim/korap/model/MultiTerm.java b/src/main/java/de/ids_mannheim/korap/model/MultiTerm.java
index 3ba5748..007f9f1 100644
--- a/src/main/java/de/ids_mannheim/korap/model/MultiTerm.java
+++ b/src/main/java/de/ids_mannheim/korap/model/MultiTerm.java
@@ -1,6 +1,7 @@
 package de.ids_mannheim.korap.model;
 
 import static de.ids_mannheim.korap.util.KorapArray.*;
+import de.ids_mannheim.korap.util.CorpusDataException;
 import org.apache.lucene.util.BytesRef;
 import java.nio.ByteBuffer;
 import java.util.*;
@@ -8,6 +9,9 @@
 import org.slf4j.Logger;
 import org.slf4j.LoggerFactory;
 
+/*
+ * Don't use ByteBuffer!
+ */
 /**
  * A MultiTerm represents a single term (e.g. a word, an annotation, a relation)
  * that can be part of a MultiTermToken.
@@ -64,7 +68,7 @@
      *
      * @param term The term surface (see synopsis).
      */
-    public MultiTerm (String term) {
+    public MultiTerm (String term) throws CorpusDataException {
         _fromString(term);
     };
 
@@ -84,7 +88,7 @@
      * @param prefix A special prefix for the term.
      * @param term The term surface (see synopsis).
      */
-    public MultiTerm (char prefix, String term) {
+    public MultiTerm (char prefix, String term) throws CorpusDataException {
         StringBuilder sb = new StringBuilder();
         _fromString(sb.append(prefix).append(':').append(term).toString());
     };
@@ -350,7 +354,7 @@
     /*
      * Deserialize MultiTerm from string representation.
      */
-    private void _fromString (String term) {
+    private void _fromString (String term) throws CorpusDataException {
         String[] termSurface = term.split("\\$", 2);
 
         // Payload is given
@@ -431,9 +435,17 @@
                     
                 }
                 catch (NumberFormatException e) {
-                    if (DEBUG)
-                        log.warn("Offset not a number: {}", term);
+                    throw new CorpusDataException(
+                        952,
+                        "Given offset information is not numeric"
+                    );
                 };
+            }
+            else {
+                throw new CorpusDataException(
+                    953,
+                    "Given offset information is incomplete"
+                );
             };
         };
         this.term = stringOffset[0];
diff --git a/src/main/java/de/ids_mannheim/korap/model/MultiTermToken.java b/src/main/java/de/ids_mannheim/korap/model/MultiTermToken.java
index 21e106f..d72433e 100644
--- a/src/main/java/de/ids_mannheim/korap/model/MultiTermToken.java
+++ b/src/main/java/de/ids_mannheim/korap/model/MultiTermToken.java
@@ -1,7 +1,13 @@
 package de.ids_mannheim.korap.model;
 
+import de.ids_mannheim.korap.util.CorpusDataException;
+
 import java.util.*;
 
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+
+
 
 /**
  *
@@ -23,6 +29,10 @@
     private short i = 0;
     private boolean sorted = false;
 
+    // This advices the java compiler to ignore all loggings
+    public static final boolean DEBUG = false;
+    private final Logger log = LoggerFactory.getLogger(MultiTermTokenStream.class);
+
     /**
      * Construct a new MultiTermToken by passing a stream of
      * {@link MultiTerm MultiTerms}.
@@ -53,10 +63,15 @@
         this.terms = new ArrayList<MultiTerm>(16);
 
         // Create a new MultiTerm
-        MultiTerm term = new MultiTerm(prefix, surface);
+        try {
+            MultiTerm term = new MultiTerm(prefix, surface);
 
-        // First word element
-        terms.add( term );
+            // First word element
+            terms.add( term );
+        }
+        catch (CorpusDataException cde) {
+            log.error("{}: {}", cde.getErrorCode(), cde.getMessage());
+        };
     };
     
 
@@ -66,18 +81,23 @@
      *
      * @param terms Take at least one {@link MultiTerm} string for a token.
      */
-    public MultiTermToken (String terms, String ... moreTerms) {
+    public MultiTermToken (String terms, String ... moreTerms) throws CorpusDataException {
         this.terms = new ArrayList<MultiTerm>(16);
 
         MultiTerm term = new MultiTerm(terms);
 
-        // First word element
-        this.terms.add( term );
+        try {
+            // First word element
+            this.terms.add( term );
 
-        // Further elements on same position
-        for (i = 0; i < moreTerms.length; i++) {
-            term = new MultiTerm( moreTerms[i] );
-            this.terms.add(term);
+            // Further elements on same position
+            for (i = 0; i < moreTerms.length; i++) {
+                term = new MultiTerm( moreTerms[i] );
+                this.terms.add(term);
+            };
+        }
+        catch (CorpusDataException cde) {
+            log.error("{}: {}", cde.getErrorCode(), cde.getMessage());
         };
     };
 
@@ -101,10 +121,18 @@
      * @param term A MultiTerm represented as a surface string.
      * @return The {@link MultiTermToken} object for chaining.
      */
-    public MultiTermToken add (String term) {
+    public MultiTermToken add (String term) throws CorpusDataException {
         if (term.length() == 0)
             return this;
-        return this.add(new MultiTerm(term));
+
+        try {
+            this.add(new MultiTerm(term));
+        }
+        catch (CorpusDataException cde) {
+            log.error("{}: {}", cde.getErrorCode(), cde.getMessage());
+        };
+
+        return this;
     };
 
 
@@ -118,7 +146,15 @@
     public MultiTermToken add (char prefix, String term) {
         if (term.length() == 0)
             return this;
-        return this.add(new MultiTerm(prefix, term));
+
+        try {
+            this.add(new MultiTerm(prefix, term));
+        }
+        catch (CorpusDataException cde) {
+            log.error("{}: {}", cde.getErrorCode(), cde.getMessage());
+        };
+
+        return this;
     };
 
 
diff --git a/src/main/java/de/ids_mannheim/korap/model/MultiTermTokenStream.java b/src/main/java/de/ids_mannheim/korap/model/MultiTermTokenStream.java
index 9ebb11b..bcc3512 100644
--- a/src/main/java/de/ids_mannheim/korap/model/MultiTermTokenStream.java
+++ b/src/main/java/de/ids_mannheim/korap/model/MultiTermTokenStream.java
@@ -1,6 +1,7 @@
 package de.ids_mannheim.korap.model;
 
 import static de.ids_mannheim.korap.util.KorapByte.*;
+import de.ids_mannheim.korap.util.CorpusDataException;
 import org.apache.lucene.util.BytesRef;
 
 import java.util.*;
@@ -72,7 +73,13 @@
      */
     public MultiTermTokenStream (String stream) {
         this();
-        this._fromString(stream);
+        try {
+            this._fromString(stream);
+        }
+        catch (CorpusDataException cde) {
+            log.error("{}: {}", cde.getErrorCode(), cde.getMessage());
+        };
+        return;
     };
 
 
@@ -92,7 +99,13 @@
         while ((j = stream.read(buf)) > 0)
             sb.append(buf, 0, j);
 
-        this._fromString(sb.toString());
+        try {
+            this._fromString(sb.toString());
+        }
+        catch (CorpusDataException cde) {
+            log.error("{}: {}", cde.getErrorCode(), cde.getMessage());
+        };
+        return;
     };
 
 
@@ -129,8 +142,7 @@
      * @param surface A surface string of a {@link MultiTerm}.
      * @return The {@link MultiTermTokenStream} object for chaining.
      */
-    public MultiTermTokenStream addMultiTermToken
-        (char prefix, String surface) {
+    public MultiTermTokenStream addMultiTermToken (char prefix, String surface) {
         return this.addMultiTermToken(new MultiTermToken(prefix, surface));
     };
 
@@ -145,10 +157,18 @@
      */
     public MultiTermTokenStream addMultiTermToken
         (String surface, String ... moreTerms) {
-        return this.addMultiTermToken(new MultiTermToken(surface, moreTerms));
+        try {
+            this.addMultiTermToken(new MultiTermToken(surface, moreTerms));
+        }
+        catch (CorpusDataException cde) {
+            log.error("{}: {}", cde.getErrorCode(), cde.getMessage());
+        };
+        return this;
     };
 
 
+
+
     /**
      * Add meta information to the MultiTermTokenStream.
      *
@@ -159,9 +179,14 @@
      * @return The {@link MultiTermTokenStream} object for chaining.
      */
     public MultiTermTokenStream addMeta (String key, String value) {
-        MultiTerm mt = new MultiTerm('-', key);
-        mt.setPayload(value);
-        this.multiTermTokens.get(0).add(mt);
+        try {
+            MultiTerm mt = new MultiTerm('-', key);
+            mt.setPayload(value);
+            this.multiTermTokens.get(0).add(mt);
+        }
+        catch (CorpusDataException cde) {
+            log.error("{}: {}", cde.getErrorCode(), cde.getMessage());
+        };
         return this;
     };
 
@@ -176,9 +201,14 @@
      * @return The {@link MultiTermTokenStream} object for chaining.
      */
     public MultiTermTokenStream addMeta (String key, byte[] value) {
-        MultiTerm mt = new MultiTerm('-', key);
-        mt.setPayload(value);
-        this.multiTermTokens.get(0).add(mt);
+        try {
+            MultiTerm mt = new MultiTerm('-', key);
+            mt.setPayload(value);
+            this.multiTermTokens.get(0).add(mt);
+        }
+        catch (CorpusDataException cde) {
+            log.error("{}: {}", cde.getErrorCode(), cde.getMessage());
+        };
         return this;
     };
 
@@ -193,9 +223,14 @@
      * @return The {@link MultiTermTokenStream} object for chaining.
      */
     public MultiTermTokenStream addMeta (String key, short value) {
-        MultiTerm mt = new MultiTerm('-', key);
-        mt.setPayload(value);
-        this.multiTermTokens.get(0).add(mt);
+        try {
+            MultiTerm mt = new MultiTerm('-', key);
+            mt.setPayload(value);
+            this.multiTermTokens.get(0).add(mt);
+        }
+        catch (CorpusDataException cde) {
+            log.error("{}: {}", cde.getErrorCode(), cde.getMessage());
+        };
         return this;
     };
 
@@ -210,9 +245,14 @@
      * @return The {@link MultiTermTokenStream} object for chaining.
      */
     public MultiTermTokenStream addMeta (String key, long value) {
-        MultiTerm mt = new MultiTerm('-', key);
-        mt.setPayload(value);
-        this.multiTermTokens.get(0).add(mt);
+        try {
+            MultiTerm mt = new MultiTerm('-', key);
+            mt.setPayload(value);
+            this.multiTermTokens.get(0).add(mt);
+        }
+        catch (CorpusDataException cde) {
+            log.error("{}: {}", cde.getErrorCode(), cde.getMessage());
+        };
         return this;
     };
 
@@ -227,9 +267,15 @@
      * @return The {@link MultiTermTokenStream} object for chaining.
      */
     public MultiTermTokenStream addMeta (String key, int value) {
-        MultiTerm mt = new MultiTerm('-', key);
-        mt.setPayload(value);
-        this.multiTermTokens.get(0).add(mt);
+        try {
+            MultiTerm mt = new MultiTerm('-', key);
+            mt.setPayload(value);
+            this.multiTermTokens.get(0).add(mt);
+        }
+        catch (CorpusDataException cde) {
+            log.error("{}: {}", cde.getErrorCode(), cde.getMessage());
+        };
+
         return this;
     };
 
@@ -273,7 +319,7 @@
 
 
     // Deserialize a string
-    private void _fromString (String stream) {
+    private void _fromString (String stream) throws CorpusDataException {
         Matcher matcher = pattern.matcher(stream);
 
         while (matcher.find()) {
@@ -282,7 +328,7 @@
 
             for (i = 1; i < seg.length; i++)
                 mtt.add(seg[i]);
-            
+
             this.addMultiTermToken(mtt);
         };
     };
@@ -293,7 +339,7 @@
      * This overrides the function in Lucene's TokenStream.
      */
     @Override
-    public final boolean incrementToken() throws IOException {
+    public final boolean incrementToken () throws IOException {
         this.payloadAttr.setPayload(null);
 
         // Last token reached
@@ -376,8 +422,8 @@
     };
 
     @Override
-    public void reset() {
+    public void reset () {
         this.mttIndex = 0;
-        this.mtIndex = 0;
+        this.mtIndex  = 0;
     };
 };
diff --git a/src/main/java/de/ids_mannheim/korap/query/spans/MatchModifyClassSpans.java b/src/main/java/de/ids_mannheim/korap/query/spans/MatchModifyClassSpans.java
index 9a1da9f..6235342 100644
--- a/src/main/java/de/ids_mannheim/korap/query/spans/MatchModifyClassSpans.java
+++ b/src/main/java/de/ids_mannheim/korap/query/spans/MatchModifyClassSpans.java
@@ -110,7 +110,8 @@
 
     @Override
     public boolean next() throws IOException {
-        if (DEBUG) log.trace("Forward next match");
+        if (DEBUG) log.trace("Forward next match in {}",
+                             this.doc());
 
         // Next span
         while (spans.next()) {
@@ -186,6 +187,7 @@
     // Todo: Check for this on document boundaries!
     @Override
     public boolean skipTo (int target) throws IOException {
+        if (DEBUG) log.trace("Skip MatchSpans");
         return spans.skipTo(target);
     };
 
diff --git a/src/main/java/de/ids_mannheim/korap/util/CorpusDataException.java b/src/main/java/de/ids_mannheim/korap/util/CorpusDataException.java
new file mode 100644
index 0000000..9b5ed23
--- /dev/null
+++ b/src/main/java/de/ids_mannheim/korap/util/CorpusDataException.java
@@ -0,0 +1,81 @@
+package de.ids_mannheim.korap.util;
+
+/**
+ * Exception class for corpus data processing problems.
+ *
+ * @author diewald
+ */
+public class CorpusDataException extends Exception {
+	
+    private int errorCode = 0;
+  
+    /**
+     * Construct a new CorpusDataException.
+     */
+    public CorpusDataException() {
+        super();
+    };
+
+
+    /**
+     * Construct a new CorpusDataException.
+     *
+     * @param message Exception message.
+     */
+    public CorpusDataException (String message) {
+        super(message);
+    };
+
+
+    /**
+     * Construct a new CorpusDataException.
+     *
+     * @param code An integer value as an error code.
+     * @param message Exception message.
+     */
+    public CorpusDataException (int code, String message) {	  
+        super(message);
+        this.setErrorCode(code);      
+    };
+
+
+    /**
+     * Construct a new CorpusDataException.
+     *
+     * @param message Exception message.
+     * @param cause A {@link Throwable} object.
+     */
+    public CorpusDataException (String message, Throwable cause) {
+        super(message, cause);
+    };
+
+
+    /**
+     * Construct a new CorpusDataException.
+     *
+     * @param cause A {@link Throwable} object.
+     */    
+    public CorpusDataException (Throwable cause) {
+        super(cause);
+    };  
+  
+
+    /**
+     * Get the error code of the exception.
+     *
+     * @return The error code of the exception as an integer.
+     */
+    public int getErrorCode() {
+        return this.errorCode;
+    };
+
+
+    /**
+     * Set the error code of the exception.
+     *
+     * @param code The error code of the exception as an integer.
+     */
+    public void setErrorCode (int code) {
+        this.errorCode = code;
+    };
+};
diff --git a/src/test/java/de/ids_mannheim/korap/Test.java b/src/test/java/de/ids_mannheim/korap/Test.java
index e8837f3..f0c5960 100644
--- a/src/test/java/de/ids_mannheim/korap/Test.java
+++ b/src/test/java/de/ids_mannheim/korap/Test.java
@@ -3,8 +3,11 @@
 import java.util.*;
 import java.io.IOException;
 
+import static org.junit.Assert.*;
+
 import de.ids_mannheim.korap.model.MultiTermTokenStream;
 import de.ids_mannheim.korap.model.MultiTermToken;
+import de.ids_mannheim.korap.util.CorpusDataException;
 
 import org.apache.lucene.document.Document;
 import org.apache.lucene.document.TextField;
@@ -15,83 +18,87 @@
 import org.apache.lucene.index.IndexWriter;
 
 /**
- * @author Nils Diewald
- *
  * Helper class for testing the KorapIndex framework (Normal).
+ *
+ * @author diewald
  */
 public class Test {
 
     public static void addDoc(IndexWriter w, Map<String, String> m) throws IOException {
-	Document doc = new Document();
-	String[] strInt = { "pubDate" };
-	String[] strStr = { "id", "corpus", "pubPlace" };
-	String[] strTxt = { "title", "subtitle", "textClass" };
+        Document doc = new Document();
+        String[] strInt = { "pubDate" };
+        String[] strStr = { "id", "corpus", "pubPlace" };
+        String[] strTxt = { "title", "subtitle", "textClass" };
 
-	// Text fields
-	for (String s : strTxt) {
-	    doc.add(new TextField(s, m.get(s), Field.Store.YES));
-	};
+        // Text fields
+        for (String s : strTxt) {
+            doc.add(new TextField(s, m.get(s), Field.Store.YES));
+        };
 
-	// String fields
-	for (String s : strStr) {
-	    doc.add(new StringField(s, m.get(s), Field.Store.YES));
-	};
+        // String fields
+        for (String s : strStr) {
+            doc.add(new StringField(s, m.get(s), Field.Store.YES));
+        };
 
-	// Integer fields
-	for (String s : strInt) {
-	    doc.add(new IntField(s, Integer.parseInt(m.get(s)), Field.Store.YES));
-	};
+        // Integer fields
+        for (String s : strInt) {
+            doc.add(new IntField(s, Integer.parseInt(m.get(s)), Field.Store.YES));
+        };
 
-	FieldType textFieldWithTermVectors = new FieldType(TextField.TYPE_STORED);
-	textFieldWithTermVectors.setStoreTermVectors(true);
-	textFieldWithTermVectors.setStoreTermVectorOffsets(true);
-	textFieldWithTermVectors.setStoreTermVectorPositions(true);
-	textFieldWithTermVectors.setStoreTermVectorPayloads(true);
+        FieldType textFieldWithTermVectors = new FieldType(TextField.TYPE_STORED);
+        textFieldWithTermVectors.setStoreTermVectors(true);
+        textFieldWithTermVectors.setStoreTermVectorOffsets(true);
+        textFieldWithTermVectors.setStoreTermVectorPositions(true);
+        textFieldWithTermVectors.setStoreTermVectorPayloads(true);
 
+        Field textFieldAnalyzed = new Field(
+            "text",
+            m.get("textStr"),
+            textFieldWithTermVectors
+        );
 
-	Field textFieldAnalyzed = new Field(
-          "text",
-          m.get("textStr"),
-	  textFieldWithTermVectors
-	);
+        MultiTermTokenStream ts = getTermVector(m.get("text"));
 
-	MultiTermTokenStream ts = getTermVector(m.get("text"));
+        textFieldAnalyzed.setTokenStream( ts );
 
-	textFieldAnalyzed.setTokenStream( ts );
+        doc.add(textFieldAnalyzed);
 
-	doc.add(textFieldAnalyzed);
-
-	// Add document to writer
-	w.addDocument(doc);
+        // Add document to writer
+        w.addDocument(doc);
     };
 
     public static MultiTermTokenStream getTermVector (String stream) {
-	MultiTermTokenStream ts = new MultiTermTokenStream();
+        MultiTermTokenStream ts = new MultiTermTokenStream();
 
-	int pos = 0;
-	for (String seg : stream.split(" ")) {
+        int pos = 0;
+        for (String seg : stream.split(" ")) {
+            
+            String[] tokseg = seg.split("\\|");
 
-	    String[] tokseg = seg.split("\\|");
+            try {
+                MultiTermToken mtt = new MultiTermToken('s', tokseg[0]);
+            
+                mtt.add("T");
+                mtt.add('i', tokseg[0].toLowerCase());
+                mtt.add('p', tokseg[1]);
+                mtt.add('l', tokseg[2]);
 
-	    MultiTermToken mtt = new MultiTermToken('s', tokseg[0]);
-
-	    mtt.add("T");
-	    mtt.add('i', tokseg[0].toLowerCase());
-	    mtt.add('p', tokseg[1]);
-	    mtt.add('l', tokseg[2]);
-
-	    if (tokseg.length == 4) {
-		for (String morph : tokseg[3].split(";")) {
-		    mtt.add('m', morph);
-		}
-	    };
-	    if (tokseg.length == 5) {
-		mtt.add('e', tokseg[4]);
-	    };
-
-	    ts.addMultiTermToken(mtt);
-	};
-
-	return ts;
+                if (tokseg.length == 4) {
+                    for (String morph : tokseg[3].split(";")) {
+                        mtt.add('m', morph);
+                    }
+                };
+                if (tokseg.length == 5) {
+                    mtt.add('e', tokseg[4]);
+                };
+                
+                ts.addMultiTermToken(mtt);
+            }
+            catch (CorpusDataException cde) {
+                fail(cde.getErrorCode() + ": " + cde.getMessage());
+            };
+        };
+        
+        return ts;
     };
 };
diff --git a/src/test/java/de/ids_mannheim/korap/TestSimple.java b/src/test/java/de/ids_mannheim/korap/TestSimple.java
index 1dd85f3..786d7a5 100644
--- a/src/test/java/de/ids_mannheim/korap/TestSimple.java
+++ b/src/test/java/de/ids_mannheim/korap/TestSimple.java
@@ -9,6 +9,7 @@
 import de.ids_mannheim.korap.model.*;
 import de.ids_mannheim.korap.query.wrap.SpanQueryWrapper;
 import de.ids_mannheim.korap.util.QueryException;
+import de.ids_mannheim.korap.util.CorpusDataException;
 
 import static de.ids_mannheim.korap.util.KorapByte.*;
 
@@ -19,140 +20,145 @@
 import org.apache.lucene.util.Bits;
 
 /**
- * @author Nils Diewald
- *
  * Helper class for testing the KorapIndex framework (Simple).
+ *
+ * @author diewald
  */
 public class TestSimple {
 
     // Add document
     public static void addDoc(IndexWriter w, Map<String, String> m) throws IOException {
-	Document doc = new Document();
+        Document doc = new Document();
 
-	FieldType textFieldWithTermVectors = new FieldType(TextField.TYPE_STORED);
-	textFieldWithTermVectors.setStoreTermVectors(true);
-	/*
-	  No offsets are stored.
-	  textFieldWithTermVectors.setStoreTermVectorOffsets(true);
-	*/
-	textFieldWithTermVectors.setStoreTermVectorPositions(true);
-	textFieldWithTermVectors.setStoreTermVectorPayloads(true);
+        FieldType textFieldWithTermVectors = new FieldType(TextField.TYPE_STORED);
+        textFieldWithTermVectors.setStoreTermVectors(true);
+        /*
+          No offsets are stored.
+          textFieldWithTermVectors.setStoreTermVectorOffsets(true);
+        */
+        textFieldWithTermVectors.setStoreTermVectorPositions(true);
+        textFieldWithTermVectors.setStoreTermVectorPayloads(true);
 
-	Field textFieldAnalyzed = new Field(
-          "text",
-          m.get("textStr"),
-	  textFieldWithTermVectors
-	);
+        Field textFieldAnalyzed = new Field(
+            "text",
+            m.get("textStr"),
+            textFieldWithTermVectors
+        );
 
-	MultiTermTokenStream ts = getTermVector(m.get("text"));
+        MultiTermTokenStream ts = getTermVector(m.get("text"));
 
-	textFieldAnalyzed.setTokenStream( ts );
+        textFieldAnalyzed.setTokenStream( ts );
 
-	doc.add(textFieldAnalyzed);
+        doc.add(textFieldAnalyzed);
 
-	// Add document to writer
-	w.addDocument(doc);
+        // Add document to writer
+        w.addDocument(doc);
     };
 
     // Get Term Vector
     public static MultiTermTokenStream getTermVector (String stream) {
-	MultiTermTokenStream ts = new MultiTermTokenStream();
+        MultiTermTokenStream ts = new MultiTermTokenStream();
 
-	int pos = 0;
-	for (String seg : stream.split(" ")) {
-	    //	    System.err.println("** Prepare " + seg);
-	    String[] tokens = seg.split("\\|");
+        int pos = 0;
+        for (String seg : stream.split(" ")) {
+            //	    System.err.println("** Prepare " + seg);
+            String[] tokens = seg.split("\\|");
 
-	    int i = 0;
+            int i = 0;
 
-	    while (tokens[i].length() == 0)
-		i++;
+            while (tokens[i].length() == 0)
+                i++;
 
-	    MultiTermToken mtt = new MultiTermToken(tokens[i]);
-	    //	    System.err.println("** Add term " + tokens[i]);
-	    i++;
-	    for (; i < tokens.length; i++) {
-		if (tokens[i].length() == 0)
-		    continue;
-		mtt.add(tokens[i]);
-	    };
-
-	    ts.addMultiTermToken(mtt);
-	};
-
-	return ts;
+            try {
+                MultiTermToken mtt = new MultiTermToken(tokens[i]);
+                //	    System.err.println("** Add term " + tokens[i]);
+                i++;
+                for (; i < tokens.length; i++) {
+                    if (tokens[i].length() == 0)
+                        continue;
+                    mtt.add(tokens[i]);
+                };
+                ts.addMultiTermToken(mtt);
+            }
+            catch (CorpusDataException cde) {
+                fail(cde.getErrorCode() + ": " + cde.getMessage());
+            };
+        };
+        
+        return ts;
     };
 
+
     // Get query wrapper based on json file
     public static SpanQueryWrapper getJSONQuery (String jsonFile) {
-	SpanQueryWrapper sqwi;
+        SpanQueryWrapper sqwi;
 	
-	try {
-	    String json = getString(jsonFile);
-	    sqwi = new KorapQuery("tokens").fromJson(json);
-	}
-	catch (QueryException e) {
-	    fail(e.getMessage());
-	    sqwi = new KorapQuery("tokens").seg("???");
-	};
-	return sqwi;
+        try {
+            String json = getString(jsonFile);
+            sqwi = new KorapQuery("tokens").fromJson(json);
+        }
+        catch (QueryException e) {
+            fail(e.getMessage());
+            sqwi = new KorapQuery("tokens").seg("???");
+        };
+        return sqwi;
     };
 
 
     // Get string
     public static String getString (String path) {
-	StringBuilder contentBuilder = new StringBuilder();
-	try {
-	    BufferedReader in = new BufferedReader(new FileReader(path));
-	    String str;
-	    while ((str = in.readLine()) != null) {
-		contentBuilder.append(str);
-	    };
-	    in.close();
-	} catch (IOException e) {
-	    fail(e.getMessage());
-	}
-	return contentBuilder.toString();
+        StringBuilder contentBuilder = new StringBuilder();
+        try {
+            BufferedReader in = new BufferedReader(new FileReader(path));
+            String str;
+            while ((str = in.readLine()) != null) {
+                contentBuilder.append(str);
+            };
+            in.close();
+        } catch (IOException e) {
+            fail(e.getMessage());
+        }
+        return contentBuilder.toString();
     };
 
 
     // getSpan Info
     public static List<String> getSpanInfo (IndexReader reader, SpanQuery query)
-	throws IOException {
-	Map<Term, TermContext> termContexts = new HashMap<>();
-	List<String> spanArray = new ArrayList<>();
+        throws IOException {
+        Map<Term, TermContext> termContexts = new HashMap<>();
+        List<String> spanArray = new ArrayList<>();
+        
+        for (AtomicReaderContext atomic : reader.leaves()) {
+            Bits bitset = atomic.reader().getLiveDocs();
+            // Spans spans = NearSpansOrdered();
+            Spans spans = query.getSpans(atomic, bitset, termContexts);
 
-	for (AtomicReaderContext atomic : reader.leaves()) {
-	    Bits bitset = atomic.reader().getLiveDocs();
-	    // Spans spans = NearSpansOrdered();
-	    Spans spans = query.getSpans(atomic, bitset, termContexts);
-
-	    while (spans.next()) {
-		StringBuffer payloadString = new StringBuffer();
-		int docid = atomic.docBase + spans.doc();
-		if (spans.isPayloadAvailable()) {
-		    for (byte[] payload : spans.getPayload()) {
-			/* retrieve payload for current matching span */
-
-			payloadString.append(byte2int(payload)).append(",");
-			payloadString.append(byte2int(payload, 2));
-			//			payloadString.append(byte2int(payload, 1));
-			payloadString.append(" (" + payload.length + ")");
-			payloadString.append(" | ");
-		    };
-		};
-		spanArray.add(
-		    "Doc: " +
-		    docid +
-		    " with " +
-		    spans.start() +
-		    "-" +
-		    spans.end() +
-		    " || " +
-		    payloadString.toString()
-		);
-	    };
-	};
-	return spanArray;
+            while (spans.next()) {
+                StringBuffer payloadString = new StringBuffer();
+                int docid = atomic.docBase + spans.doc();
+                if (spans.isPayloadAvailable()) {
+                    for (byte[] payload : spans.getPayload()) {
+                        /* retrieve payload for current matching span */
+                        
+                        payloadString.append(byte2int(payload)).append(",");
+                        payloadString.append(byte2int(payload, 2));
+                        //			payloadString.append(byte2int(payload, 1));
+                        payloadString.append(" (" + payload.length + ")");
+                        payloadString.append(" | ");
+                    };
+                };
+                spanArray.add(
+                    "Doc: " +
+                    docid +
+                    " with " +
+                    spans.start() +
+                    "-" +
+                    spans.end() +
+                    " || " +
+                    payloadString.toString()
+                );
+            };
+        };
+        return spanArray;
     };
 };
diff --git a/src/test/java/de/ids_mannheim/korap/index/TestIndex.java b/src/test/java/de/ids_mannheim/korap/index/TestIndex.java
index 94b7e8b..075b51c 100644
--- a/src/test/java/de/ids_mannheim/korap/index/TestIndex.java
+++ b/src/test/java/de/ids_mannheim/korap/index/TestIndex.java
@@ -9,6 +9,8 @@
 import de.ids_mannheim.korap.query.wrap.SpanSequenceQueryWrapper;
 import de.ids_mannheim.korap.query.SpanWithinQuery;
 
+import de.ids_mannheim.korap.util.CorpusDataException;
+
 import static de.ids_mannheim.korap.Test.*;
 
 import org.apache.lucene.analysis.standard.StandardAnalyzer;
@@ -73,7 +75,7 @@
     private Directory index = new RAMDirectory();
 
     @Test
-    public void multiTermToken () {
+    public void multiTermToken () throws CorpusDataException {
 	MultiTermToken test = new MultiTermToken("hunde", "pos:n", "m:gen:pl");
 	assertEquals(test.terms.get(0).term, "hunde");
 	assertEquals(test.terms.get(1).term, "pos:n");
diff --git a/src/test/java/de/ids_mannheim/korap/index/TestKorapIndex.java b/src/test/java/de/ids_mannheim/korap/index/TestKorapIndex.java
index 417a8b4..1c07163 100644
--- a/src/test/java/de/ids_mannheim/korap/index/TestKorapIndex.java
+++ b/src/test/java/de/ids_mannheim/korap/index/TestKorapIndex.java
@@ -23,84 +23,89 @@
 
     @Test
     public void indexExample () throws IOException {
-	KorapIndex ki = new KorapIndex();
+        KorapIndex ki = new KorapIndex();
 
-	assertEquals(0, ki.numberOf("base", "documents"));
-	assertEquals(0, ki.numberOf("base", "tokens"));
-	assertEquals(0, ki.numberOf("base", "sentences"));
-	assertEquals(0, ki.numberOf("base", "paragraphs"));
+        assertEquals(0, ki.numberOf("base", "documents"));
+        assertEquals(0, ki.numberOf("base", "tokens"));
+        assertEquals(0, ki.numberOf("base", "sentences"));
+        assertEquals(0, ki.numberOf("base", "paragraphs"));
 
-	FieldDocument fd = new FieldDocument();
+        FieldDocument fd = new FieldDocument();
 
-	fd.addString("name", "Peter");
-	fd.addInt("zahl1", 56);
-	fd.addInt("zahl2", "58");
-	fd.addText("teaser", "Das ist der Name der Rose");
-	fd.addTV("base", "ich bau", "[(0-3)s:ich|l:ich|p:PPER|-:sentences#-$<i>2][(4-7)s:bau|l:bauen|p:VVFIN]");
-	ki.addDoc(fd);
+        fd.addString("name", "Peter");
+        fd.addInt("zahl1", 56);
+        fd.addInt("zahl2", "58");
+        fd.addText("teaser", "Das ist der Name der Rose");
+        fd.addTV("base",
+                 "ich bau",
+                 "[(0-3)s:ich|l:ich|p:PPER|-:sentences$<i>2]" +
+                 "[(4-7)s:bau|l:bauen|p:VVFIN]");
+        ki.addDoc(fd);
 
-	fd = new FieldDocument();
+        fd = new FieldDocument();
 
-	fd.addString("name", "Hans");
-	fd.addInt("zahl1", 14);
-	fd.addText("teaser", "Das Sein");
+        fd.addString("name", "Hans");
+        fd.addInt("zahl1", 14);
+        fd.addText("teaser", "Das Sein");
 
-	MultiTermTokenStream mtts = fd.newMultiTermTokenStream();
-	mtts.addMultiTermToken("s:wir#0-3", "l:wir", "p:PPER");
-	mtts.addMultiTermToken("s:sind#4-8", "l:sein", "p:VVFIN");
-	mtts.addMeta("sentences", (int) 5);
-	fd.addTV("base", "wir sind", mtts);
+        MultiTermTokenStream mtts = fd.newMultiTermTokenStream();
+        mtts.addMultiTermToken("s:wir#0-3", "l:wir", "p:PPER");
+        mtts.addMultiTermToken("s:sind#4-8", "l:sein", "p:VVFIN");
+        mtts.addMeta("sentences", (int) 5);
+        fd.addTV("base", "wir sind", mtts);
+        
+        ki.addDoc(fd);
 
-	ki.addDoc(fd);
+        /* Save documents */
+        ki.commit();
 
-	/* Save documents */
-	ki.commit();
+        assertEquals(2, ki.numberOf("base", "documents"));
+        assertEquals(7, ki.numberOf("base", "sentences"));
 
-	assertEquals(2, ki.numberOf("base", "documents"));
-	assertEquals(7, ki.numberOf("base", "sentences"));
+        fd = new FieldDocument();
 
+        fd.addString("name", "Frank");
+        fd.addInt("zahl1", 59);
+        fd.addInt("zahl2", 65);
+        fd.addText("teaser", "Noch ein Versuch");
+        fd.addTV("base",
+                 "ich bau",
+                 "[(0-3)s:der|l:der|p:DET|-:sentences$<i>3]" +
+                 "[(4-8)s:baum|l:baum|p:NN]");
+        ki.addDoc(fd);
 
-	fd = new FieldDocument();
+        /* Save documents */
+        ki.commit();
 
-	fd.addString("name", "Frank");
-	fd.addInt("zahl1", 59);
-	fd.addInt("zahl2", 65);
-	fd.addText("teaser", "Noch ein Versuch");
-	fd.addTV("base", "ich bau", "[(0-3)s:der|l:der|p:DET|-:sentences#-$<i>3][(4-8)s:baum|l:baum|p:NN]");
-	ki.addDoc(fd);
+        assertEquals(3, ki.numberOf("base", "documents"));
+        assertEquals(10, ki.numberOf("base", "sentences"));
 
-	/* Save documents */
-	ki.commit();
-
-	assertEquals(3, ki.numberOf("base", "documents"));
-	assertEquals(10, ki.numberOf("base", "sentences"));
-
-	// KorapQuery kq = new KorapQuery("text");
-	// ki.search();
+        // KorapQuery kq = new KorapQuery("text");
+        // ki.search();
     };
 
     @Test
     public void indexAlteration () throws IOException {
-	KorapIndex ki = new KorapIndex();
+        KorapIndex ki = new KorapIndex();
+        
+        assertEquals(0, ki.numberOf("base", "documents"));
 
-	assertEquals(0, ki.numberOf("base", "documents"));
+        FieldDocument fd = new FieldDocument();
+        fd.addString("name", "Peter");
+        ki.addDoc(fd);
+        
+        assertEquals(0, ki.numberOf("base", "documents"));
 
-	FieldDocument fd = new FieldDocument();
-	fd.addString("name", "Peter");
-	ki.addDoc(fd);
+        fd = new FieldDocument();
+        fd.addString("name", "Michael");
+        ki.addDoc(fd);
 
-	assertEquals(0, ki.numberOf("base", "documents"));
+        assertEquals(0, ki.numberOf("base", "documents"));
 
-	fd = new FieldDocument();
-	fd.addString("name", "Michael");
-	ki.addDoc(fd);
+        ki.commit();
 
-	assertEquals(0, ki.numberOf("base", "documents"));
+        assertEquals(2, ki.numberOf("base", "documents"));
 
-	ki.commit();
-
-	assertEquals(2, ki.numberOf("base", "documents"));
-
-	// hasDeletions, hasPendingMerges
+        // hasDeletions, hasPendingMerges
     };
 };
diff --git a/src/test/java/de/ids_mannheim/korap/index/TestMatchIndex.java b/src/test/java/de/ids_mannheim/korap/index/TestMatchIndex.java
index 59c8fce..f4e4a8d 100644
--- a/src/test/java/de/ids_mannheim/korap/index/TestMatchIndex.java
+++ b/src/test/java/de/ids_mannheim/korap/index/TestMatchIndex.java
@@ -17,11 +17,8 @@
 import de.ids_mannheim.korap.KorapQuery;
 import de.ids_mannheim.korap.KorapMatch;
 import de.ids_mannheim.korap.KorapResult;
-import de.ids_mannheim.korap.query.SpanNextQuery;
-import de.ids_mannheim.korap.query.SpanElementQuery;
-import de.ids_mannheim.korap.query.SpanWithinQuery;
-import de.ids_mannheim.korap.query.SpanMatchModifyClassQuery;
-import de.ids_mannheim.korap.query.SpanClassQuery;
+import de.ids_mannheim.korap.KorapCollection;
+import de.ids_mannheim.korap.query.*;
 import de.ids_mannheim.korap.index.FieldDocument;
 import de.ids_mannheim.korap.model.MultiTermTokenStream;
 
@@ -44,17 +41,17 @@
 	// abcabcabac
 	FieldDocument fd = new FieldDocument();
 	fd.addTV("base",
-		 "abcabcabac",
-		 "[(0-1)s:a|i:a|_0#0-1|-:t$<i>10]" +
-		 "[(1-2)s:b|i:b|_1#1-2]" +
-		 "[(2-3)s:c|i:c|_2#2-3]" +
-		 "[(3-4)s:a|i:a|_3#3-4]" +
-		 "[(4-5)s:b|i:b|_4#4-5]" +
-		 "[(5-6)s:c|i:c|_5#5-6]" +
-		 "[(6-7)s:a|i:a|_6#6-7]" +
-		 "[(7-8)s:b|i:b|_7#7-8]" +
-		 "[(8-9)s:a|i:a|_8#8-9]" +
-		 "[(9-10)s:c|i:c|_9#9-10]");
+             "abcabcabac",
+             "[(0-1)s:a|i:a|_0#0-1|-:t$<i>10]" +
+             "[(1-2)s:b|i:b|_1#1-2]" +
+             "[(2-3)s:c|i:c|_2#2-3]" +
+             "[(3-4)s:a|i:a|_3#3-4]" +
+             "[(4-5)s:b|i:b|_4#4-5]" +
+             "[(5-6)s:c|i:c|_5#5-6]" +
+             "[(6-7)s:a|i:a|_6#6-7]" +
+             "[(7-8)s:b|i:b|_7#7-8]" +
+             "[(8-9)s:a|i:a|_8#8-9]" +
+             "[(9-10)s:c|i:c|_9#9-10]");
 	ki.addDoc(fd);
 
 	ki.commit();
@@ -214,200 +211,284 @@
 
     @Test
     public void indexExample2 () throws IOException {
-	KorapIndex ki = new KorapIndex();
+        KorapIndex ki = new KorapIndex();
 
-	// abcabcabac
-	FieldDocument fd = new FieldDocument();
-	fd.addTV("base",
-		 "abcabcabac",
-		 "[(0-1)s:a|i:a|_0#0-1|-:t$<i>10]" +
-		 "[(1-2)s:b|i:b|_1#1-2]" +
-		 "[(2-3)s:c|i:c|_2#2-3]" +
-		 "[(3-4)s:a|i:a|_3#3-4]" +
-		 "[(4-5)s:b|i:b|_4#4-5]" +
-		 "[(5-6)s:c|i:c|_5#5-6]" +
-		 "[(6-7)s:a|i:a|_6#6-7]" +
-		 "[(7-8)s:b|i:b|_7#7-8]" +
-		 "[(8-9)s:a|i:a|_8#8-9]" +
-		 "[(9-10)s:c|i:c|_9#9-10]");
-	ki.addDoc(fd);
+        // abcabcabac
+        FieldDocument fd = new FieldDocument();
+        fd.addTV("base",
+                 "abcabcabac",
+                 "[(0-1)s:a|i:a|_0#0-1|-:t$<i>10]" +
+                 "[(1-2)s:b|i:b|_1#1-2]" +
+                 "[(2-3)s:c|i:c|_2#2-3]" +
+                 "[(3-4)s:a|i:a|_3#3-4]" +
+                 "[(4-5)s:b|i:b|_4#4-5]" +
+                 "[(5-6)s:c|i:c|_5#5-6]" +
+                 "[(6-7)s:a|i:a|_6#6-7]" +
+                 "[(7-8)s:b|i:b|_7#7-8]" +
+                 "[(8-9)s:a|i:a|_8#8-9]" +
+                 "[(9-10)s:c|i:c|_9#9-10]");
+        ki.addDoc(fd);
+        ki.commit();
 
-	ki.commit();
+        SpanQuery sq;
+        KorapResult kr;
 
-	SpanQuery sq;
-	KorapResult kr;
-
-	// No contexts:
-	sq = new SpanOrQuery(
+        // No contexts:
+        sq = new SpanOrQuery(
             new SpanTermQuery(new Term("base", "s:a")),
-	    new SpanTermQuery(new Term("base", "s:c"))
+            new SpanTermQuery(new Term("base", "s:c"))
         );
-	kr = ki.search(sq, (short) 20);
+        kr = ki.search(sq, (short) 20);
 
-	assertEquals("totalResults", kr.getTotalResults(), 7);
-	assertEquals("SnippetBrackets (0)", "<span class=\"context-left\"></span><span class=\"match\">a</span><span class=\"context-right\">bcabca<span class=\"more\"></span></span>", kr.getMatch(0).getSnippetHTML());
-	assertEquals("SnippetBrackets (0)", "[a]bcabca ...", kr.getMatch(0).getSnippetBrackets());
+        assertEquals("totalResults", kr.getTotalResults(), 7);
+        assertEquals("SnippetBrackets (0)", "<span class=\"context-left\"></span><span class=\"match\">a</span><span class=\"context-right\">bcabca<span class=\"more\"></span></span>", kr.getMatch(0).getSnippetHTML());
+        assertEquals("SnippetBrackets (0)", "[a]bcabca ...", kr.getMatch(0).getSnippetBrackets());
 
-	assertEquals("SnippetBrackets (1)", "ab[c]abcaba ...", kr.getMatch(1).getSnippetBrackets());
-	assertEquals("SnippetBrackets (1)", "<span class=\"context-left\">ab</span><span class=\"match\">c</span><span class=\"context-right\">abcaba<span class=\"more\"></span></span>", kr.getMatch(1).getSnippetHTML());
+        assertEquals("SnippetBrackets (1)", "ab[c]abcaba ...", kr.getMatch(1).getSnippetBrackets());
+        assertEquals("SnippetBrackets (1)", "<span class=\"context-left\">ab</span><span class=\"match\">c</span><span class=\"context-right\">abcaba<span class=\"more\"></span></span>", kr.getMatch(1).getSnippetHTML());
+        
+        assertEquals("SnippetBrackets (6)", "... abcaba[c]", kr.getMatch(6).getSnippetBrackets());
+        assertEquals("SnippetBrackets (6)", "<span class=\"context-left\"><span class=\"more\"></span>abcaba</span><span class=\"match\">c</span><span class=\"context-right\"></span>", kr.getMatch(6).getSnippetHTML());
 
-	assertEquals("SnippetBrackets (6)", "... abcaba[c]", kr.getMatch(6).getSnippetBrackets());
-	assertEquals("SnippetBrackets (6)", "<span class=\"context-left\"><span class=\"more\"></span>abcaba</span><span class=\"match\">c</span><span class=\"context-right\"></span>", kr.getMatch(6).getSnippetHTML());
+        kr = ki.search(sq, 0, (short) 20, true, (short) 0, true, (short) 0);
 
-	kr = ki.search(sq, 0, (short) 20, true, (short) 0, true, (short) 0);
+        assertEquals("totalResults", kr.getTotalResults(), 7);
+        assertEquals("SnippetBrackets (0)", "[a] ...", kr.getMatch(0).getSnippetBrackets());
+        assertEquals("SnippetHTML (0)", "<span class=\"context-left\"></span><span class=\"match\">a</span><span class=\"context-right\"><span class=\"more\"></span></span>", kr.getMatch(0).getSnippetHTML());
 
-	assertEquals("totalResults", kr.getTotalResults(), 7);
-	assertEquals("SnippetBrackets (0)", "[a] ...", kr.getMatch(0).getSnippetBrackets());
-	assertEquals("SnippetHTML (0)", "<span class=\"context-left\"></span><span class=\"match\">a</span><span class=\"context-right\"><span class=\"more\"></span></span>", kr.getMatch(0).getSnippetHTML());
+        assertEquals("SnippetBrackets (1)", "... [c] ...", kr.getMatch(1).getSnippetBrackets());
+        assertEquals("SnippetHTML (1)", "<span class=\"context-left\"><span class=\"more\"></span></span><span class=\"match\">c</span><span class=\"context-right\"><span class=\"more\"></span></span>", kr.getMatch(1).getSnippetHTML());
 
-	assertEquals("SnippetBrackets (1)", "... [c] ...", kr.getMatch(1).getSnippetBrackets());
-	assertEquals("SnippetHTML (1)", "<span class=\"context-left\"><span class=\"more\"></span></span><span class=\"match\">c</span><span class=\"context-right\"><span class=\"more\"></span></span>", kr.getMatch(1).getSnippetHTML());
-
-	assertEquals("SnippetBrackets (6)", "... [c]", kr.getMatch(6).getSnippetBrackets());
-	assertEquals("SnippetBrackets (6)", "<span class=\"context-left\"><span class=\"more\"></span></span><span class=\"match\">c</span><span class=\"context-right\"></span>", kr.getMatch(6).getSnippetHTML());
+        assertEquals("SnippetBrackets (6)", "... [c]", kr.getMatch(6).getSnippetBrackets());
+        assertEquals("SnippetBrackets (6)", "<span class=\"context-left\"><span class=\"more\"></span></span><span class=\"match\">c</span><span class=\"context-right\"></span>", kr.getMatch(6).getSnippetHTML());
     };
 
 
     @Test
     public void indexExample3 () throws Exception {
-	KorapIndex ki = new KorapIndex();
+        KorapIndex ki = new KorapIndex();
 
-	// abcabcabac
-	FieldDocument fd = new FieldDocument();
-	fd.addTV("base",
-		 "abcabcabac",
-		 "[(0-1)s:a|i:a|_0#0-1|-:t$<i>10]" +
-		 "[(1-2)s:b|i:b|_1#1-2]" +
-		 "[(2-3)s:c|i:c|_2#2-3]" +
-		 "[(3-4)s:a|i:a|_3#3-4]" +
-		 "[(4-5)s:b|i:b|_4#4-5]" +
-		 "[(5-6)s:c|i:c|_5#5-6]" +
-		 "[(6-7)s:a|i:a|_6#6-7]" +
-		 "[(7-8)s:b|i:b|_7#7-8]" +
-		 "[(8-9)s:a|i:a|_8#8-9]" +
-		 "[(9-10)s:c|i:c|_9#9-10]");
-	ki.addDoc(fd);
+        // abcabcabac
+        FieldDocument fd = new FieldDocument();
+        fd.addTV("base",
+                 "abcabcabac",
+                 "[(0-1)s:a|i:a|_0#0-1|-:t$<i>10]" +
+                 "[(1-2)s:b|i:b|_1#1-2]" +
+                 "[(2-3)s:c|i:c|_2#2-3]" +
+                 "[(3-4)s:a|i:a|_3#3-4]" +
+                 "[(4-5)s:b|i:b|_4#4-5]" +
+                 "[(5-6)s:c|i:c|_5#5-6]" +
+                 "[(6-7)s:a|i:a|_6#6-7]" +
+                 "[(7-8)s:b|i:b|_7#7-8]" +
+                 "[(8-9)s:a|i:a|_8#8-9]" +
+                 "[(9-10)s:c|i:c|_9#9-10]");
+        ki.addDoc(fd);
+        ki.commit();
 
-	ki.commit();
+        KorapResult kr;
 
-	KorapResult kr;
+        KorapQuery kq = new KorapQuery("base");
 
-	KorapQuery kq = new KorapQuery("base");
+        SpanQuery sq = kq._(1,kq.seq(kq.seg("s:b")).append(kq.seg("s:a")).append(kq._(2,kq.seg("s:c")))).toQuery();
+        
+        kr = ki.search(sq, 0, (short) 20, true, (short) 2, true, (short) 5);
 
-	SpanQuery sq = kq._(1,kq.seq(kq.seg("s:b")).append(kq.seg("s:a")).append(kq._(2,kq.seg("s:c")))).toQuery();
-
-	kr = ki.search(sq, 0, (short) 20, true, (short) 2, true, (short) 5);
-
-	assertEquals("totalResults", kr.getTotalResults(), 1);
-	assertEquals("SnippetBrackets (0)", "... ca[{1:ba{2:c}}]", kr.getMatch(0).getSnippetBrackets());
+        assertEquals("totalResults", kr.getTotalResults(), 1);
+        assertEquals("SnippetBrackets (0)", "... ca[{1:ba{2:c}}]", kr.getMatch(0).getSnippetBrackets());
     };
 
 
     @Test
     public void indexExampleExtend () throws IOException {
-	KorapIndex ki = new KorapIndex();
+        KorapIndex ki = new KorapIndex();
 
-	// abcabcabac
-	FieldDocument fd = new FieldDocument();
-	fd.addTV("base",
-		 "abcabcabac",
-		 "[(0-1)s:a|i:a|_0#0-1|-:t$<i>10]" +
-		 "[(1-2)s:b|i:b|_1#1-2]" +
-		 "[(2-3)s:c|i:c|_2#2-3]" +
-		 "[(3-4)s:a|i:a|_3#3-4]" +
-		 "[(4-5)s:b|i:b|_4#4-5]" +
-		 "[(5-6)s:c|i:c|_5#5-6]" +
-		 "[(6-7)s:a|i:a|_6#6-7]" +
-		 "[(7-8)s:b|i:b|_7#7-8]" +
-		 "[(8-9)s:a|i:a|_8#8-9]" +
-		 "[(9-10)s:c|i:c|_9#9-10]");
-	ki.addDoc(fd);
+        // abcabcabac
+        FieldDocument fd = new FieldDocument();
+        fd.addTV("base",
+                 "abcabcabac",
+                 "[(0-1)s:a|i:a|_0#0-1|-:t$<i>10]" +
+                 "[(1-2)s:b|i:b|_1#1-2]" +
+                 "[(2-3)s:c|i:c|_2#2-3]" +
+                 "[(3-4)s:a|i:a|_3#3-4]" +
+                 "[(4-5)s:b|i:b|_4#4-5]" +
+                 "[(5-6)s:c|i:c|_5#5-6]" +
+                 "[(6-7)s:a|i:a|_6#6-7]" +
+                 "[(7-8)s:b|i:b|_7#7-8]" +
+                 "[(8-9)s:a|i:a|_8#8-9]" +
+                 "[(9-10)s:c|i:c|_9#9-10]");
+        ki.addDoc(fd);
+        ki.commit();
 
-	ki.commit();
+        SpanQuery sq;
+        KorapResult kr;
 
-	SpanQuery sq;
-	KorapResult kr;
-
-	sq = new SpanMatchModifyClassQuery(
+        sq = new SpanMatchModifyClassQuery(
             new SpanNextQuery(
-	        new SpanClassQuery(new SpanTermQuery(new Term("base", "s:a")), (byte) 2),
+                new SpanClassQuery(new SpanTermQuery(new Term("base", "s:a")), (byte) 2),
                 new SpanClassQuery(new SpanTermQuery(new Term("base", "s:b")), (byte) 3)
             ), (byte) 3
         );
 
-	kr = ki.search(sq, (short) 10);
+        kr = ki.search(sq, (short) 10);
 
-	assertEquals("totalResults", kr.getTotalResults(), 3);
+        assertEquals("totalResults", kr.getTotalResults(), 3);
 
-	KorapMatch km = kr.getMatch(0);
-	assertEquals("StartPos (0)", 1, km.startPos);
-	assertEquals("EndPos (0)", 2, km.endPos);
-	assertEquals("SnippetBrackets (0)", "a[{3:b}]cabcab ...", km.getSnippetBrackets());
+        KorapMatch km = kr.getMatch(0);
+        assertEquals("StartPos (0)", 1, km.startPos);
+        assertEquals("EndPos (0)", 2, km.endPos);
+        assertEquals("SnippetBrackets (0)", "a[{3:b}]cabcab ...", km.getSnippetBrackets());
 
-	sq = new SpanMatchModifyClassQuery(
-	    new SpanMatchModifyClassQuery(
+        sq = new SpanMatchModifyClassQuery(
+            new SpanMatchModifyClassQuery(
                 new SpanNextQuery(
 	            new SpanClassQuery(new SpanTermQuery(new Term("base", "s:a")), (byte) 2),
                     new SpanClassQuery(new SpanTermQuery(new Term("base", "s:b")), (byte) 3)
                 ), (byte) 3
-	    ), (byte) 2
-	);
+	        ), (byte) 2
+        );
 	
-	kr = ki.search(sq, (short) 10);
+        kr = ki.search(sq, (short) 10);
 
-	km = kr.getMatch(0);
-	assertEquals("StartPos (0)", 0, km.startPos);
-	assertEquals("EndPos (0)", 1, km.endPos);
-	assertEquals("SnippetBrackets (0)", "[{2:a}]bcabca ...", km.getSnippetBrackets());
+        km = kr.getMatch(0);
+        assertEquals("StartPos (0)", 0, km.startPos);
+        assertEquals("EndPos (0)", 1, km.endPos);
+        assertEquals("SnippetBrackets (0)", "[{2:a}]bcabca ...", km.getSnippetBrackets());
 
-
-	// TODO: Check ID
+        // TODO: Check ID
     };
 
 
     @Test
     public void indexExampleFocusWithSpan () throws IOException {
-	KorapIndex ki = new KorapIndex();
+        KorapIndex ki = new KorapIndex();
+        
+        // abcabcabac
+        FieldDocument fd = new FieldDocument();
+        fd.addTV("base",
+                 "abcabcabac",
+                 "[(0-1)s:a|i:a|_0#0-1|-:t$<i>10]" +
+                 "[(1-2)s:b|i:b|_1#1-2|<>:s#1-5$<i>5]" +
+                 "[(2-3)s:c|i:c|_2#2-3|<>:s#2-7$<i>7]" +
+                 "[(3-4)s:a|i:a|_3#3-4]" +
+                 "[(4-5)s:b|i:b|_4#4-5]" +
+                 "[(5-6)s:c|i:c|_5#5-6]" +
+                 "[(6-7)s:a|i:a|_6#6-7]" +
+                 "[(7-8)s:b|i:b|_7#7-8]" +
+                 "[(8-9)s:a|i:a|_8#8-9]" +
+                 "[(9-10)s:c|i:c|_9#9-10]");
+        ki.addDoc(fd);
+        ki.commit();
 
-	// abcabcabac
-	FieldDocument fd = new FieldDocument();
-	fd.addTV("base",
-		 "abcabcabac",
-		 "[(0-1)s:a|i:a|_0#0-1|-:t$<i>10]" +
-		 "[(1-2)s:b|i:b|_1#1-2|<>:s#1-5$<i>5]" +
-		 "[(2-3)s:c|i:c|_2#2-3|<>:s#2-7$<i>7]" +
-		 "[(3-4)s:a|i:a|_3#3-4]" +
-		 "[(4-5)s:b|i:b|_4#4-5]" +
-		 "[(5-6)s:c|i:c|_5#5-6]" +
-		 "[(6-7)s:a|i:a|_6#6-7]" +
-		 "[(7-8)s:b|i:b|_7#7-8]" +
-		 "[(8-9)s:a|i:a|_8#8-9]" +
-		 "[(9-10)s:c|i:c|_9#9-10]");
-	ki.addDoc(fd);
-
-	ki.commit();
-
-	SpanQuery sq;
-	KorapResult kr;
-
-	sq = new SpanWithinQuery(
-	    new SpanClassQuery(new SpanElementQuery("base", "s"), (byte) 2),
+        SpanQuery sq;
+        KorapResult kr;
+        
+        sq = new SpanWithinQuery(
+            new SpanClassQuery(new SpanElementQuery("base", "s"), (byte) 2),
             new SpanClassQuery(new SpanTermQuery(new Term("base", "s:b")), (byte) 3)
         );
 
-	kr = ki.search(sq, (short) 10);
-	assertEquals(kr.getQuery(), "spanContain({2: <base:s />}, {3: base:s:b})");
-	assertEquals(kr.getMatch(0).getSnippetBrackets(), "a[{2:{3:b}cab}]cabac");
+        kr = ki.search(sq, (short) 10);
+        assertEquals(kr.getQuery(), "spanContain({2: <base:s />}, {3: base:s:b})");
+        assertEquals(kr.getMatch(0).getSnippetBrackets(), "a[{2:{3:b}cab}]cabac");
 
-	sq = new SpanMatchModifyClassQuery(
+        sq = new SpanMatchModifyClassQuery(
             new SpanWithinQuery(
 	        new SpanClassQuery(new SpanElementQuery("base", "s"), (byte) 2),
                 new SpanClassQuery(new SpanTermQuery(new Term("base", "s:b")), (byte) 3)
             ), (byte) 3
         );
 
-	kr = ki.search(sq, (short) 10);
-	assertEquals(kr.getQuery(), "focus(3: spanContain({2: <base:s />}, {3: base:s:b}))");
-	assertEquals(kr.getMatch(0).getSnippetBrackets(), "a[{3:b}]cabcab ...");
+        kr = ki.search(sq, (short) 10);
+        assertEquals(kr.getQuery(), "focus(3: spanContain({2: <base:s />}, {3: base:s:b}))");
+        assertEquals(kr.getMatch(0).getSnippetBrackets(), "a[{3:b}]cabcab ...");
     };
+
+
+    @Test
+    public void indexExampleFocusWithSkip () throws IOException {
+        KorapIndex ki = new KorapIndex();
+        
+        // abcabcabac
+        FieldDocument fd = new FieldDocument();
+        // The payload should be ignored
+        fd.addTV("base",
+                 "abcabcabac",
+                 "[(0-1)s:a|i:a|_0#0-1|-:t$<i>10]" + // |<>:p#0-10<i>9]" +
+                 "[(1-2)s:b|i:b|_1#1-2|<>:s#1-5$<i>5]" +
+                 "[(2-3)s:c|i:c|_2#2-3|<>:s#2-7$<i>7]" +
+                 "[(3-4)s:a|i:a|_3#3-4]" +
+                 "[(4-5)s:b|i:b|_4#4-5]" +
+                 "[(5-6)s:c|i:c|_5#5-6]" +
+                 "[(6-7)s:a|i:a|_6#6-7]" +
+                 "[(7-8)s:b|i:b|_7#7-8]" +
+                 "[(8-9)s:a|i:a|_8#8-9]" +
+                 "[(9-10)s:c|i:c|_9#9-10]");
+
+        ki.addDoc(fd);
+        fd.addTV("base",
+                 "gbcgbcgbgc",
+                 "[(0-1)s:g|i:g|_0#0-1|-:t$<i>10|<>:p#0-10$<i>9]" +
+                 "[(1-2)s:b|i:b|_1#1-2|<>:s#1-5$<i>5]" +
+                 "[(2-3)s:c|i:c|_2#2-3|<>:s#2-7$<i>7]" +
+                 "[(3-4)s:g|i:g|_3#3-4]" +
+                 "[(4-5)s:b|i:b|_4#4-5]" +
+                 "[(5-6)s:c|i:c|_5#5-6]" +
+                 "[(6-7)s:g|i:g|_6#6-7]" +
+                 "[(7-8)s:b|i:b|_7#7-8]" +
+                 "[(8-9)s:g|i:g|_8#8-9]" +
+                 "[(9-10)s:c|i:c|_9#9-10]");
+        ki.addDoc(fd);
+        fd.addTV("base",
+                 "gbcgbcgbgc",
+                 "[(0-1)s:g|i:g|_0#0-1|-:t$<i>10]" +
+                 "[(1-2)s:b|i:b|_1#1-2]" +
+                 "[(2-3)s:c|i:c|_2#2-3]" +
+                 "[(3-4)s:g|i:g|_3#3-4]" +
+                 "[(4-5)s:b|i:b|_4#4-5]" +
+                 "[(5-6)s:c|i:c|_5#5-6]" +
+                 "[(6-7)s:g|i:g|_6#6-7]" +
+                 "[(7-8)s:b|i:b|_7#7-8]" +
+                 "[(8-9)s:g|i:g|_8#8-9]" +
+                 "[(9-10)s:c|i:c|_9#9-10]");
+        ki.addDoc(fd);
+        fd.addTV("base",
+                 "abcabcabac",
+                 "[(0-1)s:a|i:a|_0#0-1|-:t$<i>10|<>:p#0-10$<i>9]" +
+                 "[(1-2)s:b|i:b|_1#1-2|<>:s#1-5$<i>5]" +
+                 "[(2-3)s:c|i:c|_2#2-3|<>:s#2-7$<i>7]" +
+                 "[(3-4)s:a|i:a|_3#3-4]" +
+                 "[(4-5)s:b|i:b|_4#4-5]" +
+                 "[(5-6)s:c|i:c|_5#5-6]" +
+                 "[(6-7)s:a|i:a|_6#6-7]" +
+                 "[(7-8)s:b|i:b|_7#7-8]" +
+                 "[(8-9)s:a|i:a|_8#8-9]" +
+                 "[(9-10)s:c|i:c|_9#9-10]");
+        ki.addDoc(fd);
+        ki.commit();
+
+        SpanQuery sq;
+        KorapResult kr;
+        KorapCollection kc = new KorapCollection(ki);
+
+        assertEquals("Documents", 4, kc.numberOf("documents"));
+
+        sq = new SpanWithinQuery(
+                 new SpanElementQuery("base", "p"),
+                 new SpanMatchModifyClassQuery(
+                     new SpanWithinQuery(
+                         new SpanClassQuery(new SpanElementQuery("base", "s"), (byte) 2),
+                         new SpanClassQuery(new SpanTermQuery(new Term("base", "s:a")), (byte) 3)
+                     ), (byte) 3
+                 )
+             );
+
+        fail("Skipping may go horribly wrong! (Known issue)");
+        kr = kc.search(sq);
+        assertEquals(kr.getQuery(), "spanContain(<base:p />, focus(3: spanContain({2: <base:s />}, {3: base:s:a})))");
+        assertEquals(12, kr.getTotalResults());
+        assertEquals("[a{2:bc{3:a}b}cabac]", kr.getMatch(0).getSnippetBrackets());
+        assertEquals("[ab{2:c{3:a}bcab}ac]", kr.getMatch(1).getSnippetBrackets());
+        assertEquals("[ab{2:cabc{3:a}}bac]", kr.getMatch(2).getSnippetBrackets());
+    };
+
 };
diff --git a/src/test/java/de/ids_mannheim/korap/model/TestMultiTerm.java b/src/test/java/de/ids_mannheim/korap/model/TestMultiTerm.java
index 8ee1bd4..715c1f0 100644
--- a/src/test/java/de/ids_mannheim/korap/model/TestMultiTerm.java
+++ b/src/test/java/de/ids_mannheim/korap/model/TestMultiTerm.java
@@ -2,6 +2,7 @@
 
 import java.util.*;
 import de.ids_mannheim.korap.model.MultiTerm;
+import de.ids_mannheim.korap.util.CorpusDataException;
 import java.io.IOException;
 import org.apache.lucene.util.BytesRef;
 
@@ -15,7 +16,7 @@
 @RunWith(JUnit4.class)
 public class TestMultiTerm {
     @Test
-    public void multiTermSimple () {
+    public void multiTermSimple () throws CorpusDataException {
         MultiTerm mt = new MultiTerm("test");
         assertEquals(mt.term, "test");
         assertNull(mt.payload);
@@ -24,7 +25,7 @@
     };
 
     @Test
-    public void multiTermPayload () {
+    public void multiTermPayload () throws CorpusDataException {
         MultiTerm mt = new MultiTerm("test$5");
         assertEquals("test", mt.term);
         assertEquals(new BytesRef("5"), mt.payload);
@@ -33,7 +34,7 @@
     };
 
     @Test
-    public void multiTermOffset () {
+    public void multiTermOffset () throws CorpusDataException {
         MultiTerm mt = new MultiTerm("versuch#2-34");
         assertEquals(mt.term, "versuch");
         assertNull(mt.payload);
@@ -42,7 +43,7 @@
     };
 
     @Test
-    public void multiTermOffsetPayload () {
+    public void multiTermOffsetPayload () throws CorpusDataException {
         MultiTerm mt = new MultiTerm("example#6-42$hihi");
         assertEquals(mt.term, "example");
         assertEquals(new BytesRef("hihi"), mt.payload);
@@ -51,7 +52,7 @@
     };
 
     @Test
-    public void multiTermString () {
+    public void multiTermString () throws CorpusDataException {
         MultiTerm mt = new MultiTerm("example#6-42$hihi");
         assertEquals("example#6-42$hihi", mt.toString());
         mt.term = "spassmacher";
@@ -59,7 +60,7 @@
     };
 
     @Test
-    public void multiTermStringPayloadType () {
+    public void multiTermStringPayloadType () throws CorpusDataException {
         MultiTerm mt = new MultiTerm("example$<i>4000");
         assertEquals("example$<?>[0,0,f,a0]", mt.toString());
 
@@ -68,7 +69,7 @@
     };
     
     @Test
-    public void multiTermStringPayloadType2 () {
+    public void multiTermStringPayloadType2 () throws CorpusDataException {
         MultiTerm mt = new MultiTerm();
         mt.setTerm("beispiel");
         mt.setStart(40);
@@ -80,19 +81,19 @@
     };
 
     @Test
-    public void multiTermStringPayloadType3 () {
+    public void multiTermStringPayloadType3 () throws CorpusDataException {
         MultiTerm mt = new MultiTerm("example$<b>120");
         assertEquals("example$x", mt.toString());
     };
 
     @Test
-    public void multiTermStringPayloadType4 () {
+    public void multiTermStringPayloadType4 () throws CorpusDataException {
         MultiTerm mt = new MultiTerm("example$<i>420<b>120");
         assertEquals("example$<?>[0,0,1,a4,78]", mt.toString());
     };
 
     @Test
-    public void multiTermStringPayloadType5 () {
+    public void multiTermStringPayloadType5 () throws CorpusDataException {
         MultiTerm mt = new MultiTerm("example$<i>4000");
         assertEquals("example$<?>[0,0,f,a0]", mt.toString());
 
@@ -104,7 +105,7 @@
     };
 
     @Test
-    public void multiTermStringFail () {
+    public void multiTermStringFail () throws CorpusDataException {
         MultiTerm mt = new MultiTerm("example#56-66");
         assertEquals(56, mt.getStart());
         assertEquals(66,mt.getEnd());
@@ -113,9 +114,15 @@
         assertEquals(56, mt.getStart());
         assertEquals(66, mt.getEnd());
 
-        mt = new MultiTerm("example#56$<i>a");
-        assertEquals(mt.getPayload(), null);
-        assertEquals(mt.getStart(), 0);
-        assertEquals(mt.getEnd(), 0);
+        try {
+            mt = new MultiTerm("example#56$<i>a");
+            assertEquals(mt.getPayload(), null);
+            assertEquals(mt.getStart(), 0);
+            assertEquals(mt.getEnd(), 0);
+        }
+        catch (CorpusDataException cde) {
+            // Works fine!
+            assertTrue(true);
+        };
     };
 };
diff --git a/src/test/java/de/ids_mannheim/korap/model/TestMultiTermToken.java b/src/test/java/de/ids_mannheim/korap/model/TestMultiTermToken.java
index 3e301ee..0b36001 100644
--- a/src/test/java/de/ids_mannheim/korap/model/TestMultiTermToken.java
+++ b/src/test/java/de/ids_mannheim/korap/model/TestMultiTermToken.java
@@ -2,6 +2,7 @@
 
 import java.util.*;
 import de.ids_mannheim.korap.model.MultiTermToken;
+import de.ids_mannheim.korap.util.CorpusDataException;
 import java.io.IOException;
 import org.apache.lucene.util.BytesRef;
 
@@ -18,7 +19,7 @@
 public class TestMultiTermToken {
 
     @Test
-    public void multiTermTokenSimple () {
+    public void multiTermTokenSimple () throws CorpusDataException {
         MultiTermToken mtt = new MultiTermToken("t:test", "a:abbruch");
         assertEquals("[t:test|a:abbruch]", mtt.toString());
         mtt.add("b:banane");
@@ -38,7 +39,7 @@
     };
 
     @Test
-    public void multiTermTokenOffsets () {
+    public void multiTermTokenOffsets () throws CorpusDataException {
         MultiTermToken mtt = new MultiTermToken("t:test#23-27");
         assertEquals("[t:test#23-27]", mtt.toString());
         mtt.add("b:baum#34-45");
diff --git a/src/test/java/de/ids_mannheim/korap/model/TestMultiTermTokenStream.java b/src/test/java/de/ids_mannheim/korap/model/TestMultiTermTokenStream.java
index f1e3597..3a1fcff 100644
--- a/src/test/java/de/ids_mannheim/korap/model/TestMultiTermTokenStream.java
+++ b/src/test/java/de/ids_mannheim/korap/model/TestMultiTermTokenStream.java
Binary files differ
diff --git a/src/test/java/de/ids_mannheim/korap/query/TestFrameConstraint.java b/src/test/java/de/ids_mannheim/korap/query/TestFrameConstraint.java
index 019c949..4600248 100644
--- a/src/test/java/de/ids_mannheim/korap/query/TestFrameConstraint.java
+++ b/src/test/java/de/ids_mannheim/korap/query/TestFrameConstraint.java
@@ -1,7 +1,12 @@
 package de.ids_mannheim.korap.query;
 
+import java.io.IOException;
+import java.util.Collection;
+
 import de.ids_mannheim.korap.query.FrameConstraint;
 import de.ids_mannheim.korap.util.QueryException;
+import org.apache.lucene.search.spans.Spans;
+
 
 import static org.junit.Assert.*;
 import org.junit.Test;
@@ -197,4 +202,53 @@
         assertEquals(fc1.check("succeedsDirectly"), true);
         assertEquals(fc1.check("succeeds"),         true);
     };
+
+    private class TestSpans extends Spans {
+        private int s, e;
+
+        @Override
+        public int doc () {
+            return 0;
+        };
+
+        @Override
+        public int start () {
+            return this.s;
+        };
+
+        @Override
+        public int end () {
+            return this.e;
+        };
+
+        @Override
+        public boolean skipTo (int target) {
+            return true;
+        };
+
+        @Override
+        public boolean next () {
+            return true;
+        };
+
+        public Collection<byte[]> getPayload() throws IOException {
+            return null;
+        }
+
+        @Override
+        public boolean isPayloadAvailable() throws IOException {
+            return false;
+        };
+
+        @Override
+        public String toString () {				
+            return "";
+        };
+
+        @Override
+        public long cost () {				
+            return 1;
+        };
+
+    };
 };
diff --git a/src/test/java/de/ids_mannheim/korap/query/TestSpanSequenceQueryJSON.java b/src/test/java/de/ids_mannheim/korap/query/TestSpanSequenceQueryJSON.java
index e1378fe..8545881 100644
--- a/src/test/java/de/ids_mannheim/korap/query/TestSpanSequenceQueryJSON.java
+++ b/src/test/java/de/ids_mannheim/korap/query/TestSpanSequenceQueryJSON.java
@@ -26,229 +26,229 @@
 
     @Test
     public void queryJSONseqEmpty () throws QueryException {
-	SpanQueryWrapper sqwi = jsonQueryFile("empty.jsonld");
+        SpanQueryWrapper sqwi = jsonQueryFile("empty.jsonld");
 
-	// []
-	assertTrue(sqwi.isEmpty());
+        // []
+        assertTrue(sqwi.isEmpty());
     };
 
     @Test
     public void queryJSONseqEmptyEnd () throws QueryException {
-	SpanQueryWrapper sqwi = jsonQueryFile("empty-last.jsonld");
-	assertEquals(sqwi.toQuery().toString(), "spanExpansion(tokens:s:der, []{1, 1}, right)");
+        SpanQueryWrapper sqwi = jsonQueryFile("empty-last.jsonld");
+        assertEquals(sqwi.toQuery().toString(), "spanExpansion(tokens:s:der, []{1, 1}, right)");
     };
 
     @Test
     public void queryJSONseqEmptyEndClass () throws QueryException {
-	SpanQueryWrapper sqwi = jsonQueryFile("empty-last-class.jsonld");
-	// der{3:[]}
-	assertEquals(sqwi.toQuery().toString(), "spanExpansion(tokens:s:der, []{1, 1}, right, class:3)");
+        SpanQueryWrapper sqwi = jsonQueryFile("empty-last-class.jsonld");
+        // der{3:[]}
+        assertEquals(sqwi.toQuery().toString(), "spanExpansion(tokens:s:der, []{1, 1}, right, class:3)");
     };
 
     @Test
     public void queryJSONseqEmptyEndRepetition () throws QueryException {
-	SpanQueryWrapper sqwi = jsonQueryFile("empty-last-repetition.jsonld");
-	// der[]{3,5}
-	assertEquals(sqwi.toQuery().toString(), "spanExpansion(tokens:s:der, []{3, 5}, right)");
+        SpanQueryWrapper sqwi = jsonQueryFile("empty-last-repetition.jsonld");
+        // der[]{3,5}
+        assertEquals(sqwi.toQuery().toString(), "spanExpansion(tokens:s:der, []{3, 5}, right)");
     };
 
     @Test
     public void queryJSONseqEmptyStart () throws QueryException {
-	SpanQueryWrapper sqwi = jsonQueryFile("empty-first.jsonld");
-	// [][tt/p=NN]
-	assertEquals(sqwi.toQuery().toString(), "spanExpansion(tokens:tt/p:NN, []{1, 1}, left)");
+        SpanQueryWrapper sqwi = jsonQueryFile("empty-first.jsonld");
+        // [][tt/p=NN]
+        assertEquals(sqwi.toQuery().toString(), "spanExpansion(tokens:tt/p:NN, []{1, 1}, left)");
     };
 
     @Test
     public void queryJSONseqEmptyStartClass () throws QueryException {
-	SpanQueryWrapper sqwi = jsonQueryFile("empty-first-class.jsonld");
-	// {2:[]}[tt/p=NN]
-	assertEquals(sqwi.toQuery().toString(), "spanExpansion(tokens:tt/p:NN, []{1, 1}, left, class:2)");
+        SpanQueryWrapper sqwi = jsonQueryFile("empty-first-class.jsonld");
+        // {2:[]}[tt/p=NN]
+        assertEquals(sqwi.toQuery().toString(), "spanExpansion(tokens:tt/p:NN, []{1, 1}, left, class:2)");
     };
 
     @Test
     public void queryJSONseqEmptyStartRepetition () throws QueryException {
-	SpanQueryWrapper sqwi = jsonQueryFile("empty-first-repetition.jsonld");
-	// []{2,7}[tt/p=NN]
-	assertEquals(sqwi.toQuery().toString(), "spanExpansion(tokens:tt/p:NN, []{2, 7}, left)");
+        SpanQueryWrapper sqwi = jsonQueryFile("empty-first-repetition.jsonld");
+        // []{2,7}[tt/p=NN]
+        assertEquals(sqwi.toQuery().toString(), "spanExpansion(tokens:tt/p:NN, []{2, 7}, left)");
     };
 
     @Test
     public void queryJSONseqEmptyStartRepetition2 () throws QueryException {
-	SpanQueryWrapper sqwi = jsonQueryFile("empty-first-repetition-2.jsonld");
-	// []{0,0}[tt/p=NN]
-	assertEquals(sqwi.toQuery().toString(), "tokens:tt/p:NN");
+        SpanQueryWrapper sqwi = jsonQueryFile("empty-first-repetition-2.jsonld");
+        // []{0,0}[tt/p=NN]
+        assertEquals(sqwi.toQuery().toString(), "tokens:tt/p:NN");
     };
 
     @Test
     public void queryJSONseqEmptyMiddle () throws QueryException {
-	SpanQueryWrapper sqwi = jsonQueryFile("empty-middle.jsonld");
-	// der[][tt/p=NN]
-	assertEquals(sqwi.toQuery().toString(), "spanNext(tokens:s:der, spanExpansion(tokens:tt/p:NN, []{1, 1}, left))");
+        SpanQueryWrapper sqwi = jsonQueryFile("empty-middle.jsonld");
+        // der[][tt/p=NN]
+        assertEquals(sqwi.toQuery().toString(), "spanNext(tokens:s:der, spanExpansion(tokens:tt/p:NN, []{1, 1}, left))");
     };
 
     @Test
     public void queryJSONseqEmptyMiddleClass () throws QueryException {
-	SpanQueryWrapper sqwi = jsonQueryFile("empty-middle-class.jsonld");
-	// der{1:[]}[tt/p=NN]
-	assertEquals(sqwi.toQuery().toString(), "spanNext(tokens:s:der, spanExpansion(tokens:tt/p:NN, []{1, 1}, left, class:1))");
+        SpanQueryWrapper sqwi = jsonQueryFile("empty-middle-class.jsonld");
+        // der{1:[]}[tt/p=NN]
+        assertEquals(sqwi.toQuery().toString(), "spanNext(tokens:s:der, spanExpansion(tokens:tt/p:NN, []{1, 1}, left, class:1))");
     };
 
     @Test
     public void queryJSONseqEmptyMiddleRepetition () throws QueryException {
-	SpanQueryWrapper sqwi = jsonQueryFile("empty-middle-repetition.jsonld");
-	// der[]{4,8}[tt/p=NN]
-	assertEquals(sqwi.toQuery().toString(), "spanNext(tokens:s:der, spanExpansion(tokens:tt/p:NN, []{4, 8}, left))");
+        SpanQueryWrapper sqwi = jsonQueryFile("empty-middle-repetition.jsonld");
+        // der[]{4,8}[tt/p=NN]
+        assertEquals(sqwi.toQuery().toString(), "spanNext(tokens:s:der, spanExpansion(tokens:tt/p:NN, []{4, 8}, left))");
     };
 
     @Test
     public void queryJSONseqEmptySurround () throws QueryException {
-	SpanQueryWrapper sqwi = jsonQueryFile("empty-surround.jsonld");
-	// [][tt/p=NN][]
-	assertEquals(sqwi.toQuery().toString(), "spanExpansion(spanExpansion(tokens:tt/p:NN, []{1, 1}, left), []{1, 1}, right)");
+        SpanQueryWrapper sqwi = jsonQueryFile("empty-surround.jsonld");
+        // [][tt/p=NN][]
+        assertEquals(sqwi.toQuery().toString(), "spanExpansion(spanExpansion(tokens:tt/p:NN, []{1, 1}, left), []{1, 1}, right)");
     };
 
     @Test
     public void queryJSONseqEmptySurroundClass () throws QueryException {
-	SpanQueryWrapper sqwi = jsonQueryFile("empty-surround-class.jsonld");
-	// [][tt/p=NN]{2:[]}
-	assertEquals(sqwi.toQuery().toString(), "spanExpansion(spanExpansion(tokens:tt/p:NN, []{1, 1}, left), []{1, 1}, right, class:2)");
+        SpanQueryWrapper sqwi = jsonQueryFile("empty-surround-class.jsonld");
+        // [][tt/p=NN]{2:[]}
+        assertEquals(sqwi.toQuery().toString(), "spanExpansion(spanExpansion(tokens:tt/p:NN, []{1, 1}, left), []{1, 1}, right, class:2)");
     };
 
     @Test
     public void queryJSONseqEmptySurroundClass2 () throws QueryException {
-	SpanQueryWrapper sqwi = jsonQueryFile("empty-surround-class-2.jsonld");
-	// {3:[]}[tt/p=NN]{2:[]}
-	assertEquals(sqwi.toQuery().toString(), "spanExpansion(spanExpansion(tokens:tt/p:NN, []{1, 1}, left, class:3), []{1, 1}, right, class:2)");
+        SpanQueryWrapper sqwi = jsonQueryFile("empty-surround-class-2.jsonld");
+        // {3:[]}[tt/p=NN]{2:[]}
+        assertEquals(sqwi.toQuery().toString(), "spanExpansion(spanExpansion(tokens:tt/p:NN, []{1, 1}, left, class:3), []{1, 1}, right, class:2)");
     };
 
     @Test
     public void queryJSONseqEmptySurroundRepetition () throws QueryException {
-	SpanQueryWrapper sqwi = jsonQueryFile("empty-surround-repetition.jsonld");
-	// [][tt/p=NN][]{2,7}
-	assertEquals(sqwi.toQuery().toString(), "spanExpansion(spanExpansion(tokens:tt/p:NN, []{1, 1}, left), []{2, 7}, right)");
+        SpanQueryWrapper sqwi = jsonQueryFile("empty-surround-repetition.jsonld");
+        // [][tt/p=NN][]{2,7}
+        assertEquals(sqwi.toQuery().toString(), "spanExpansion(spanExpansion(tokens:tt/p:NN, []{1, 1}, left), []{2, 7}, right)");
     };
 
     @Test
     public void queryJSONseqEmptySurroundRepetition2 () throws QueryException {
-	SpanQueryWrapper sqwi = jsonQueryFile("empty-surround-repetition-2.jsonld");
-	// []{3,5}[tt/p=NN][]{2,7}
-	assertEquals(sqwi.toQuery().toString(), "spanExpansion(spanExpansion(tokens:tt/p:NN, []{3, 5}, left), []{2, 7}, right)");
+        SpanQueryWrapper sqwi = jsonQueryFile("empty-surround-repetition-2.jsonld");
+        // []{3,5}[tt/p=NN][]{2,7}
+        assertEquals(sqwi.toQuery().toString(), "spanExpansion(spanExpansion(tokens:tt/p:NN, []{3, 5}, left), []{2, 7}, right)");
     };
 
     @Test
     public void queryJSONseqEmptySurroundRepetitionClass () throws QueryException {
-	SpanQueryWrapper sqwi = jsonQueryFile("empty-surround-repetition-class.jsonld");
-	// {1:[]}{3,8}[tt/p=NN]{2:[]{2,7}}
-	// Ist gleichbedeutend mit
-	// {1:[]{3,8}}[tt/p=NN]{2:[]}{2,7}
-	assertEquals(sqwi.toQuery().toString(), "spanExpansion(spanExpansion(tokens:tt/p:NN, []{3, 8}, left, class:1), []{2, 7}, right, class:2)");
+        SpanQueryWrapper sqwi = jsonQueryFile("empty-surround-repetition-class.jsonld");
+        // {1:[]}{3,8}[tt/p=NN]{2:[]{2,7}}
+        // Ist gleichbedeutend mit
+        // {1:[]{3,8}}[tt/p=NN]{2:[]}{2,7}
+        assertEquals(sqwi.toQuery().toString(), "spanExpansion(spanExpansion(tokens:tt/p:NN, []{3, 8}, left, class:1), []{2, 7}, right, class:2)");
     };
 
     @Test
     public void queryJSONseqNegative () throws QueryException {
-	SpanQueryWrapper sqwi = jsonQueryFile("negative.jsonld");
-	// [tt/p!=NN]
-	assertTrue(sqwi.isNegative());
+        SpanQueryWrapper sqwi = jsonQueryFile("negative.jsonld");
+        // [tt/p!=NN]
+        assertTrue(sqwi.isNegative());
     };
 
     @Test
     public void queryJSONseqNegativeStart () throws QueryException {
-	SpanQueryWrapper sqwi = jsonQueryFile("negative-first.jsonld");
-	// [tt/p!=NN][tt/p=NN]
-	assertEquals(sqwi.toQuery().toString(), "spanExpansion(tokens:tt/p:NN, !tokens:tt/p:NN{1, 1}, left)");
+        SpanQueryWrapper sqwi = jsonQueryFile("negative-first.jsonld");
+        // [tt/p!=NN][tt/p=NN]
+        assertEquals(sqwi.toQuery().toString(), "spanExpansion(tokens:tt/p:NN, !tokens:tt/p:NN{1, 1}, left)");
     };
 
     @Test
     public void queryJSONseqNegativeEnd () throws QueryException {
-	SpanQueryWrapper sqwi = jsonQueryFile("negative-last.jsonld");
-	// [tt/p=NN][tt/p!=NN]
-	assertEquals(sqwi.toQuery().toString(), "spanExpansion(tokens:tt/p:NN, !tokens:tt/p:NN{1, 1}, right)");
+        SpanQueryWrapper sqwi = jsonQueryFile("negative-last.jsonld");
+        // [tt/p=NN][tt/p!=NN]
+        assertEquals(sqwi.toQuery().toString(), "spanExpansion(tokens:tt/p:NN, !tokens:tt/p:NN{1, 1}, right)");
     };
 
     @Test
     public void queryJSONseqNegativeStartRepetition () throws QueryException {
-	SpanQueryWrapper sqwi = jsonQueryFile("negative-first-repetition.jsonld");
-	// [tt/p!=NN]{4,5}[tt/p=NN]
-	assertEquals(sqwi.toQuery().toString(), "spanExpansion(tokens:tt/p:NN, !tokens:tt/p:NN{4, 5}, left)");
+        SpanQueryWrapper sqwi = jsonQueryFile("negative-first-repetition.jsonld");
+        // [tt/p!=NN]{4,5}[tt/p=NN]
+        assertEquals(sqwi.toQuery().toString(), "spanExpansion(tokens:tt/p:NN, !tokens:tt/p:NN{4, 5}, left)");
     };
 
     @Test
     public void queryJSONseqNegativeStartRepetition2 () throws QueryException {
-	SpanQueryWrapper sqwi = jsonQueryFile("negative-first-repetition-2.jsonld");
-	// [tt/p!=NN]{0,5}[tt/p=NN]
-	assertEquals(sqwi.toQuery().toString(), "spanExpansion(tokens:tt/p:NN, !tokens:tt/p:NN{0, 5}, left)");
+        SpanQueryWrapper sqwi = jsonQueryFile("negative-first-repetition-2.jsonld");
+        // [tt/p!=NN]{0,5}[tt/p=NN]
+        assertEquals(sqwi.toQuery().toString(), "spanExpansion(tokens:tt/p:NN, !tokens:tt/p:NN{0, 5}, left)");
     };
 
     @Test
     public void queryJSONseqNegativeStartRepetition3 () throws QueryException {
-	SpanQueryWrapper sqwi = jsonQueryFile("negative-first-repetition-3.jsonld");
-	// [tt/p!=NN]{0,0}[tt/p=NN]
-	assertEquals(sqwi.toQuery().toString(), "tokens:tt/p:NN");
+        SpanQueryWrapper sqwi = jsonQueryFile("negative-first-repetition-3.jsonld");
+        // [tt/p!=NN]{0,0}[tt/p=NN]
+        assertEquals(sqwi.toQuery().toString(), "tokens:tt/p:NN");
     };
 
     @Test
     public void queryJSONseqNegativeEndClass () throws QueryException {
-	SpanQueryWrapper sqwi = jsonQueryFile("negative-last-class.jsonld");
-	// [tt/p=NN]{2:[tt/p!=NN]}
-	SpanQuery sq = sqwi.toQuery();
-	assertEquals(sq.toString(), "spanExpansion(tokens:tt/p:NN, !tokens:tt/p:NN{1, 1}, right, class:2)");
+        SpanQueryWrapper sqwi = jsonQueryFile("negative-last-class.jsonld");
+        // [tt/p=NN]{2:[tt/p!=NN]}
+        SpanQuery sq = sqwi.toQuery();
+        assertEquals(sq.toString(), "spanExpansion(tokens:tt/p:NN, !tokens:tt/p:NN{1, 1}, right, class:2)");
     };
 
     @Test
     public void queryJSONseqNegativeEndRepetitionClass () throws QueryException {
-	SpanQueryWrapper sqwi = jsonQueryFile("negative-last-class-repetition.jsonld");
-	// [tt/p=NN]{2:[tt/p!=NN]{4,5}}
-	assertEquals(sqwi.toQuery().toString(), "spanExpansion(tokens:tt/p:NN, !tokens:tt/p:NN{4, 5}, right, class:2)");
+        SpanQueryWrapper sqwi = jsonQueryFile("negative-last-class-repetition.jsonld");
+        // [tt/p=NN]{2:[tt/p!=NN]{4,5}}
+        assertEquals(sqwi.toQuery().toString(), "spanExpansion(tokens:tt/p:NN, !tokens:tt/p:NN{4, 5}, right, class:2)");
     };
 
     @Test
     public void queryJSONseqNegativeEndRepetitionClass2 () throws QueryException {
-	SpanQueryWrapper sqwi = jsonQueryFile("negative-last-class-repetition-2.jsonld");
-	// [tt/p=NN]{2:[tt/p!=NN]}{4,5}
-	assertEquals(sqwi.toQuery().toString(), "spanExpansion(tokens:tt/p:NN, !tokens:tt/p:NN{4, 5}, right, class:2)");
+        SpanQueryWrapper sqwi = jsonQueryFile("negative-last-class-repetition-2.jsonld");
+        // [tt/p=NN]{2:[tt/p!=NN]}{4,5}
+        assertEquals(sqwi.toQuery().toString(), "spanExpansion(tokens:tt/p:NN, !tokens:tt/p:NN{4, 5}, right, class:2)");
     };
 
     @Test
     public void queryJSONseqNegativelastConstraint () {
-	SpanQueryWrapper sqwi = jsonQueryFile("negative-last-constraint.jsonld");
-	try {
-	    sqwi.toQuery().toString();
-	    fail("Should throw an exception");
-	}
-	catch (QueryException qe) {
-	    assertEquals("Distance constraints not supported with empty or negative operands", qe.getMessage());
-	};
+        SpanQueryWrapper sqwi = jsonQueryFile("negative-last-constraint.jsonld");
+        try {
+            sqwi.toQuery().toString();
+            fail("Should throw an exception");
+        }
+        catch (QueryException qe) {
+            assertEquals("Distance constraints not supported with empty or negative operands", qe.getMessage());
+        };
     };
 
     @Test
     public void queryJSONseqNegativeEndSequence () throws QueryException {
-	SpanQueryWrapper sqwi = jsonQueryFile("negative-last-sequence.jsonld");
-	// [tt/p=NN]([tt/p!=DET][tt/p!=NN])
-	assertEquals("spanExpansion(spanExpansion(tokens:tt/p:NN, !tokens:tt/p:DET{1, 1}, right), !tokens:tt/p:ADJ{1, 1}, right)", sqwi.toQuery().toString());
+        SpanQueryWrapper sqwi = jsonQueryFile("negative-last-sequence.jsonld");
+        // [tt/p=NN]([tt/p!=DET][tt/p!=NN])
+        assertEquals("spanExpansion(spanExpansion(tokens:tt/p:NN, !tokens:tt/p:DET{1, 1}, right), !tokens:tt/p:ADJ{1, 1}, right)", sqwi.toQuery().toString());
     };
 
 
     @Test
     public void queryJSONseqNegativeEndSequence2 () throws QueryException {
-	SpanQueryWrapper sqwi = jsonQueryFile("negative-last-sequence-2.jsonld");
-	// [tt/p!=NN]([tt/p!=DET][tt/p=NN])
+        SpanQueryWrapper sqwi = jsonQueryFile("negative-last-sequence-2.jsonld");
+        // [tt/p!=NN]([tt/p!=DET][tt/p=NN])
 
-	// spanNext(tokens:tt/p:NN, 
-	assertEquals("spanExpansion(spanExpansion(tokens:tt/p:ADJ, !tokens:tt/p:DET{1, 1}, left), !tokens:tt/p:NN{1, 1}, left)", sqwi.toQuery().toString());
+        // spanNext(tokens:tt/p:NN, 
+        assertEquals("spanExpansion(spanExpansion(tokens:tt/p:ADJ, !tokens:tt/p:DET{1, 1}, left), !tokens:tt/p:NN{1, 1}, left)", sqwi.toQuery().toString());
     };
 
     @Test
     public void queryJSONseqMultipleDistances () throws QueryException {
-	SpanQueryWrapper sqwi = jsonQueryFile("multiple-distances.jsonld");
-	// er []{,10} kann []{1,10} sagte 
+        SpanQueryWrapper sqwi = jsonQueryFile("multiple-distances.jsonld");
+        // er []{,10} kann []{1,10} sagte 
 
-	assertEquals("spanDistance(tokens:s:er, spanDistance(tokens:s:kann, tokens:s:sagte, [(w[2:11], ordered, notExcluded)]), [(w[1:11], ordered, notExcluded)])", sqwi.toQuery().toString());
+        assertEquals("spanDistance(tokens:s:er, spanDistance(tokens:s:kann, tokens:s:sagte, [(w[2:11], ordered, notExcluded)]), [(w[1:11], ordered, notExcluded)])", sqwi.toQuery().toString());
     };
 
 
     // get query wrapper based on json file
     public SpanQueryWrapper jsonQueryFile (String filename) {
-	return getJSONQuery(getClass().getResource(path + filename).getFile());
+        return getJSONQuery(getClass().getResource(path + filename).getFile());
     };
 };