The community seems to favor moving all import/export files (.crn, .xsl, etc) to a single package: org.jasig.portal.io.

Furthermore, import scripts (and related files) should be suffixed with an Object Model version (e.g. import-user_v2-6.crn). This approach will allow exported documents to refer to the version that imports them. When there's a change to the object model, a new script (w/ the new version) will be created and the old one will transform/add content and invoke the new script.

Export scripts do no require versioning because a single portal is only responsible for exporting to it's own native format.