From MathWeb

The OWL-DL implementation of the OMDoc document ontology is modular, roughly one OWL-DL file per module (see chapter 22.3 of the OMDoc book) of the OMDoc XML schema.

One-file version

The XSL transformation onefile.xsl creates a one-file version of the modular ontology for compatibility reasons. You can find its output in onefile/omdoc.owl. Note that the implementation of onefile.xsl is still rather naïve; if a file (here: base.owl) is included from two other files (here: st.owl and pf.owl), its elements occur twice in the output. Jena does not complain about that, however. If we should run into problems, there are three alternatives:

1. weed out the one-file version manually
2. improve onefile.xsl
3. reimplement it in Java using Jena: first import, then export (see ticket:1390)

Tools

Note that Protégé versions <= 3.2 do not work with the modular ontology.

References

• owl:imports in the OWL reference
• Tutorial
• Formal background (I haven't read these papers, just found them. --Clange 14:36, 12 July 2006 (CEST))
  • Paper on modular ontologies
  • Modularization Algorithm