Advanced Schema Extenders
This covers some of the edge cases for schema extenders, including tying one extender to multiple content types, and having multiple extenders per type.
Allowing multiple extender products to extend one content type
Using "named extenders" to permit multiple schema extender products to extend a single content type.
Using one schema extender for multiple content types
You may need to add a field to multiple content types. In this example, we'll apply the FolderImageExtender to Events as well as Folders.