In the final release of SED-ML we decided to use urns to describe what language is being used by a model for example:
<model id="model1" language="urn:sedml:language:sbml" source="00001-sbml-l3v1.xml" />
However if this is read into jlibsedml and written out again it shows up as:
<model id="model1" language="SBML (Generic)" source="00001-sbml-l3v1.xml">
this really should be a urn!
This is already fixed.... at some point over the last 5 years ....