The Primary Term modules allows you to specify which taxonomy term should be the "primary" term for a node. For nodes that can have multiple terms from a single vocabulary, a primary term can specify which summary page the node should be listed on, which theme template to apply, etc.
After being more or less unmaintained for 2 years, I've fixed a bunch of bugs and added new features and integrated with a bunch of core modules, based on code people have submitted in the issue queue since the last time it was actively maintained. New features in 6.x-1.2 include:
- CTools / Panels support.
- Context support.
- Taxonomy Role support.
- Views field display fixes.
- Now works with Hierarchical Select and Content Taxonomy.
- You can now make the Primary Term field required.
- You can now specify custom titles for the Primary Field form element per content type
- Now implements CCK's hook_content_extra_fields() so the widget can be placed as desired via the Manage Fields page.
- I18n internationalization support for taxonomy terms.
- Full changelog...
At this point, I am not worrying too much about updating the 5.x-1.x. There are less than ten sites currently using this branch according to the usage statistics, and it will be deprecated once D7 is released (very shortly). I will ensure the D5-D6 upgrade path remains intact.
There is currently an issue open addressing the migration of this module to D7. Since Taxonomy is now handled by the Fields API in D7, this module will be undergoing some massive changes, and may exist as little more than a custom widget and an upgrade path. For those interested, you can follow the discussion in.