This is possibly a silly question, please forgive me if that is the case: We have text files and RelaxNG schemas for them. In addition we point to DTD-fragments for defining entities. It seems that validation in Oxygen (both 12.x and 13) out-of-the-box does not check to see if entities used in the text file are declared or not, that the files are considered valid even if they use entity-names that are not used. A typical start-of-textfile may look like this: <?xml version="1.0" encoding="UTF-8"?> <!DOCTYPE TEI [ <!ENTITY % HIS_entiteter SYSTEM 'http://www.edd.uio.no/ibsen/schema/ibsen-charent.dtd' > %HIS_entiteter; ]> <?xml-model href="http://www.edd.uio.no/ibsen/schema/tei_his.rnc" type="application/relax-ng-compact-syntax"?> <TEI xmlns="http://www.tei-c.org/ns/1.0" xmlns:HIS="http://www.example.org/ns/HIS"> <teiHeader xml:lang="nob"> <fileDesc> <titleStmt> <title level="s" type="main">Henrik Ibsens skrifter</title> <title level="s" type="sub">Diplomatarisk tekstarkiv</title> <title level="a" type="main">Peer Gynt</title> <title level="a" type="sub">NBO Ms.8° 894 (trykt eksemplar med rettelser)</title> <title level="a" type="origYear">[1874]</title> What can we do to have an error flagged if [ is not declared? Best regards, Espen Ore University of Oslo