Improve handling of unknown header types

Change-Id: I5c1f0d12c9dcb11421745c0ca55865e4efc388db
diff --git a/t/data/goe_sample.i5.xml b/t/data/goe_sample.i5.xml
index e29daa5..6b52bcd 100644
--- a/t/data/goe_sample.i5.xml
+++ b/t/data/goe_sample.i5.xml
@@ -296,7 +296,7 @@
   </profileDesc>
  </idsHeader>
  <idsDoc type="text" version="1.0" TEIform="TEI.2">
-  <idsHeader type="document" pattern="text" status="new" version="1.1" TEIform="teiHeader">
+  <idsHeader type="doc" pattern="text" status="new" version="1.1" TEIform="teiHeader">
    <fileDesc>
     <titleStmt>
      <dokumentSigle>GOE/AGA</dokumentSigle>