diff --git a/src/main/java/de/ids_mannheim/korap/query/SpanElementQuery.java b/src/main/java/de/ids_mannheim/korap/query/SpanElementQuery.java
index 22ef490..cbbab44 100644
--- a/src/main/java/de/ids_mannheim/korap/query/SpanElementQuery.java
+++ b/src/main/java/de/ids_mannheim/korap/query/SpanElementQuery.java
@@ -19,7 +19,7 @@
  */
 
 /** Matches spans wrapped by an element. */
-public class SpanElementQuery extends SimpleSpanQuery {
+public class SpanElementQuery extends SpanWithIdQuery {
 	//private SpanTermQuery termQuery;
     private static Term elementTerm;
     private String elementStr;
diff --git a/src/main/java/de/ids_mannheim/korap/query/SpanRelationQuery.java b/src/main/java/de/ids_mannheim/korap/query/SpanRelationQuery.java
index 1a0ce77..27061b9 100644
--- a/src/main/java/de/ids_mannheim/korap/query/SpanRelationQuery.java
+++ b/src/main/java/de/ids_mannheim/korap/query/SpanRelationQuery.java
@@ -21,7 +21,7 @@
  *  
  *  @author margaretha
  * */
-public class SpanRelationQuery extends SimpleSpanQuery {
+public class SpanRelationQuery extends SpanWithIdQuery {
 
 	public SpanRelationQuery(SpanQuery firstClause, boolean collectPayloads) {
 		super(firstClause, collectPayloads);
diff --git a/src/main/java/de/ids_mannheim/korap/query/SpanRelationWithVariableQuery.java b/src/main/java/de/ids_mannheim/korap/query/SpanRelationWithVariableQuery.java
index c031c59..359ca75 100644
--- a/src/main/java/de/ids_mannheim/korap/query/SpanRelationWithVariableQuery.java
+++ b/src/main/java/de/ids_mannheim/korap/query/SpanRelationWithVariableQuery.java
@@ -6,7 +6,6 @@
 import org.apache.lucene.index.AtomicReaderContext;
 import org.apache.lucene.index.Term;
 import org.apache.lucene.index.TermContext;
-import org.apache.lucene.search.spans.SpanQuery;
 import org.apache.lucene.search.spans.Spans;
 import org.apache.lucene.util.Bits;
 import org.apache.lucene.util.ToStringUtils;
@@ -18,36 +17,23 @@
  * 
  * 	@author margaretha
  * */
-public class SpanRelationWithVariableQuery extends SpanRelationQuery{
+public class SpanRelationWithVariableQuery extends SpanWithIdQuery{
 	
 	private static String elementStr = "s"; // default element interval type
 	
 	private SpanElementQuery elementQuery;
 	private boolean matchRight;  // if false, match left
+	private int window;
 	
 	public SpanRelationWithVariableQuery(SpanRelationQuery spanRelationQuery,
-			SpanElementQuery secondClause, // match span
+			SpanWithIdQuery secondClause, // match tokenWithIdQuery, ElementQuery, RelationQuery
 			boolean matchRight,
 			boolean collectPayloads) {
 		this(spanRelationQuery, secondClause, elementStr, matchRight, collectPayloads);		
 	}
 	
 	public SpanRelationWithVariableQuery(SpanRelationQuery spanRelationQuery,
-			SpanTermWithIdQuery secondClause, // match token
-			boolean matchRight,
-			boolean collectPayloads) {
-		this(spanRelationQuery, secondClause, elementStr, matchRight, collectPayloads);		
-	}
-	
-	public SpanRelationWithVariableQuery(SpanRelationQuery spanRelationQuery,
-			SpanRelationQuery secondClause, // match span
-			boolean matchRight,
-			boolean collectPayloads) {
-		this(spanRelationQuery, secondClause, elementStr, matchRight, collectPayloads);		
-	}
-	
-	public SpanRelationWithVariableQuery(SpanRelationQuery spanRelationQuery,
-			SpanQuery secondClause, // match span
+			SpanWithIdQuery secondClause, 
 			String elementStr,
 			boolean matchRight,
 			boolean collectPayloads) {
@@ -56,6 +42,16 @@
 		elementQuery = new SpanElementQuery(spanRelationQuery.getField(), elementStr);		
 	}
 	
+	public SpanRelationWithVariableQuery(SpanRelationQuery spanRelationQuery,
+			SpanWithIdQuery secondClause, // match tokenWithIdQuery, ElementQuery, RelationQuery
+			int window,
+			boolean matchRight,
+			boolean collectPayloads) {
+		super(spanRelationQuery, secondClause, collectPayloads);
+		this.matchRight = matchRight;
+		this.window = window;
+	}
+	
 	@Override
 	public Spans getSpans(AtomicReaderContext context, Bits acceptDocs,
 			Map<Term, TermContext> termContexts) throws IOException {
@@ -66,7 +62,7 @@
 	public SimpleSpanQuery clone() {
 		SpanRelationWithVariableQuery sq = new SpanRelationWithVariableQuery(
 				(SpanRelationQuery) this.firstClause, 
-				this.secondClause,
+				(SpanWithIdQuery) this.secondClause,
 				this.elementQuery.getElementStr(),
 				this.matchRight, 
 				this.collectPayloads
@@ -84,8 +80,14 @@
 		sb.append(",");
 		sb.append( matchRight ? "matchRight, " : "matchLeft, " );
 		sb.append(",");
-		sb.append("element:");
-		sb.append(elementQuery.getElementStr());
+		if (elementQuery != null){
+			sb.append("element:");
+			sb.append(elementQuery.getElementStr());
+		}
+		else {
+			sb.append("window:");
+			sb.append(this.window);
+		}
 		sb.append(")");
 		sb.append(ToStringUtils.boost(getBoost()));
 		return sb.toString();
@@ -106,4 +108,12 @@
 	public void setElementQuery(SpanElementQuery root) {
 		this.elementQuery = root;
 	}
+
+	public int getWindow() {
+		return window;
+	}
+
+	public void setWindow(int window) {
+		this.window = window;
+	}
 }
diff --git a/src/main/java/de/ids_mannheim/korap/query/SpanTermWithIdQuery.java b/src/main/java/de/ids_mannheim/korap/query/SpanTermWithIdQuery.java
index 42e8305..230728a 100644
--- a/src/main/java/de/ids_mannheim/korap/query/SpanTermWithIdQuery.java
+++ b/src/main/java/de/ids_mannheim/korap/query/SpanTermWithIdQuery.java
@@ -18,7 +18,7 @@
  * 	
  * 	@author margaretha
  * */
-public class SpanTermWithIdQuery extends SimpleSpanQuery{
+public class SpanTermWithIdQuery extends SpanWithIdQuery{
 
 	public SpanTermWithIdQuery(Term term, boolean collectPayloads) {
 		super(new SpanTermQuery(term), collectPayloads);		
diff --git a/src/main/java/de/ids_mannheim/korap/query/SpanWithIdQuery.java b/src/main/java/de/ids_mannheim/korap/query/SpanWithIdQuery.java
new file mode 100644
index 0000000..d117f98
--- /dev/null
+++ b/src/main/java/de/ids_mannheim/korap/query/SpanWithIdQuery.java
@@ -0,0 +1,15 @@
+package de.ids_mannheim.korap.query;
+
+import org.apache.lucene.search.spans.SpanQuery;
+
+public abstract class SpanWithIdQuery extends SimpleSpanQuery{
+
+	public SpanWithIdQuery(SpanQuery firstClause, boolean collectPayloads) {
+		super(firstClause, collectPayloads);
+	}
+	
+	public SpanWithIdQuery(SpanQuery firstClause, SpanQuery secondClause,
+			boolean collectPayloads) {
+		super(firstClause, secondClause, collectPayloads);
+	}
+}
diff --git a/src/main/java/de/ids_mannheim/korap/query/spans/RelationSpansWithVariable.java b/src/main/java/de/ids_mannheim/korap/query/spans/RelationSpansWithVariable.java
index 63c5278..871f45a 100644
--- a/src/main/java/de/ids_mannheim/korap/query/spans/RelationSpansWithVariable.java
+++ b/src/main/java/de/ids_mannheim/korap/query/spans/RelationSpansWithVariable.java
@@ -17,9 +17,9 @@
  * 	whose left side token/element positions matching the second spans, 
  * 	or vice versa.
  * 	
- * 	Relations within a certain interval, e.g element-based or token-
- * 	distance-based, are sorted to resolve reference within that interval.
- * 	Resolution is limited only within an interval. 
+ * 	Relations within a certain window, e.g element-based or token-
+ * 	distance-based, are sorted to resolve reference within that window.
+ * 	Resolution is limited only within an window. 
  * 
  * 	@author margaretha
  * */
@@ -34,21 +34,29 @@
 	private boolean hasMoreMatchees;
 	
 	private short leftId, rightId;
+	private int window;
 	
 	public RelationSpansWithVariable(SpanRelationWithVariableQuery query,	
 			AtomicReaderContext context, Bits acceptDocs,
 			Map<Term, TermContext> termContexts) throws IOException {
-		super(query, context, acceptDocs, termContexts);		
-		element = (ElementSpans) query.getElementQuery().getSpans(context, acceptDocs, 
-				termContexts);
+		super(query, context, acceptDocs, termContexts);
+		if (query.getElementQuery() != null){
+			element = (ElementSpans) query.getElementQuery().getSpans(context, acceptDocs, 
+					termContexts);
+		}
+		else{
+			window = query.getWindow();
+		}
 		relationSpans = (RelationSpans) firstSpans;
-		matcheeSpans = (SpansWithId) secondSpans;
-		
+		matcheeSpans = (SpansWithId) secondSpans;		
 		// hack
 		matcheeSpans.hasSpanId = true;
 		
 		hasMoreMatchees = matcheeSpans.next();
-  		hasMoreSpans = element.next() && relationSpans.next() && hasMoreMatchees;
+  		hasMoreSpans = relationSpans.next() && hasMoreMatchees;
+  		if (element != null){
+  			hasMoreSpans &= element.next();
+  		}
 		candidateRelations = new ArrayList<CandidateRelationSpan>();
 		matchRight = query.isMatchRight();
 	}
@@ -79,17 +87,40 @@
 				candidateRelations.remove(0);
 				return true;
 			}
-			else {	setCandidateList(); }
+			else if (element != null){
+				setCandidateList();
+			}
+			else {	setCandidateListWithWindow(); }
 		}		
 		return false;
 	}
 
+	/** A window starts at the same token position as a relation span, 
+	 * 	and ends at the start + window length.
+	 * */
+	private void setCandidateListWithWindow() throws IOException {
+		if (hasMoreSpans && ensureSameDoc(relationSpans, matcheeSpans) ){
+			int windowEnd = relationSpans.start() + window;
+			if (relationSpans.end() > windowEnd){
+				throw new IllegalArgumentException("The window length "+window
+					+" is too small. The relation span ("+relationSpans.start()+
+					","+relationSpans.end()+") is longer than " +"the window " +
+					"length.");
+			}
+			else {
+				collectRelations(relationSpans.doc(), windowEnd);
+				// sort results
+				Collections.sort(candidateRelations);
+			}
+		}
+	}
+
 	private void setCandidateList() throws IOException {
 		while (hasMoreSpans && findSameDoc(element, relationSpans, matcheeSpans) ){
 			// if the relation is within a sentence
 			if (relationSpans.start() >= element.start() && 
 					relationSpans.end() <= element.end()){
-				collectRelations();
+				collectRelations(element.doc(),element.end());
 				// sort results
 				Collections.sort(candidateRelations);
 			}			
@@ -104,14 +135,14 @@
 
 	/** Collect all relations within an element whose left side matching the secondspans.
 	 * */
-	private void collectRelations() throws IOException {			
+	private void collectRelations(int currentDoc, int windowEnd) throws IOException {			
 		List<CandidateRelationSpan> temp = new ArrayList<CandidateRelationSpan>();
 		boolean sortRight = false;
 		if (matchRight) sortRight = true;
 		// collect all relations within an element	
 		while (hasMoreSpans &&
-				relationSpans.doc() == element.doc() &&
-				relationSpans.end() <= element.end()){
+				relationSpans.doc() == currentDoc &&
+				relationSpans.end() <= windowEnd){
 			temp.add(new CandidateRelationSpan(relationSpans,sortRight));
 			hasMoreSpans = relationSpans.next();
 		}
diff --git a/src/main/java/de/ids_mannheim/korap/query/spans/SpansWithId.java b/src/main/java/de/ids_mannheim/korap/query/spans/SpansWithId.java
index 465d11f..b851e04 100644
--- a/src/main/java/de/ids_mannheim/korap/query/spans/SpansWithId.java
+++ b/src/main/java/de/ids_mannheim/korap/query/spans/SpansWithId.java
@@ -8,9 +8,7 @@
 import org.apache.lucene.index.TermContext;
 import org.apache.lucene.util.Bits;
 
-import de.ids_mannheim.korap.query.SpanElementQuery;
-import de.ids_mannheim.korap.query.SpanRelationQuery;
-import de.ids_mannheim.korap.query.SpanTermWithIdQuery;
+import de.ids_mannheim.korap.query.SpanWithIdQuery;
 
 /** Base class for span enumeration with spanid property.
  * 	@author margaretha
@@ -20,22 +18,10 @@
 	protected short spanId;
 	protected boolean hasSpanId = false; // A dummy flag
 	
-	public SpansWithId(SpanElementQuery spanElementQuery,
+	public SpansWithId(SpanWithIdQuery spanWithIdQuery,
 			AtomicReaderContext context, Bits acceptDocs,
 			Map<Term, TermContext> termContexts) throws IOException {
-		super(spanElementQuery, context, acceptDocs, termContexts);
-	}
-	
-	public SpansWithId(SpanRelationQuery spanRelationQuery,
-			AtomicReaderContext context, Bits acceptDocs,
-			Map<Term, TermContext> termContexts) throws IOException {
-		super(spanRelationQuery, context, acceptDocs, termContexts);
-	}
-	
-	public SpansWithId(SpanTermWithIdQuery spanTermWithIdQuery,
-			AtomicReaderContext context, Bits acceptDocs,
-			Map<Term, TermContext> termContexts) throws IOException {
-		super(spanTermWithIdQuery, context, acceptDocs, termContexts);
+		super(spanWithIdQuery, context, acceptDocs, termContexts);
 	}
 
 	public short getSpanId() {
diff --git a/src/test/java/de/ids_mannheim/korap/index/TestRelationIndex.java b/src/test/java/de/ids_mannheim/korap/index/TestRelationIndex.java
index 23f9467..cccbd23 100644
--- a/src/test/java/de/ids_mannheim/korap/index/TestRelationIndex.java
+++ b/src/test/java/de/ids_mannheim/korap/index/TestRelationIndex.java
@@ -579,4 +579,38 @@
 		assertEquals(4,kr.getMatch(2).getStartPos());
 		assertEquals(5,kr.getMatch(2).getEndPos());
 	}
+	
+	/** Window
+	 * */
+	@Test
+	public void testCase9() throws IOException {
+		ki.addDoc(createFieldDoc2());
+		ki.commit();
+				
+		SpanRelationWithVariableQuery rv = new SpanRelationWithVariableQuery(
+				new SpanRelationQuery(
+						new SpanTermQuery(new Term("base",">:child-of")),true
+				), 
+				new SpanElementQuery("base","np"), 
+				6, true, true); 
+				
+		kr = ki.search(rv,(short) 10);
+		assertEquals(7, kr.getTotalResults());
+		
+		rv =new SpanRelationWithVariableQuery(
+				new SpanRelationQuery(
+						new SpanTermQuery(new Term("base","<:dep")),true
+				), 
+				new SpanTermWithIdQuery(new Term("base","pos:NN"),true), 
+				3, false, true);
+		kr = ki.search(rv,(short) 10);
+		assertEquals(3, kr.getTotalResults());
+		
+		/*for (KorapMatch km : kr.getMatches()){
+			System.out.println(km.getStartPos() +","+km.getEndPos()
+				//+" "+km.getSnippetBrackets()
+				);
+		}*/
+	}
 }
+