Martin,
I don't think that the WPS file types (named 'type associations' in the WPS) are of much use for the entire system with the current status. It seems to me that IBM never finished their thoughts about it (as for other features) and the IBM implementation was wrong:
1. Filter associations have more priority than type associations.
2. Associations added by classes can't be overridden by any other settings. They always come before other filter and type assocs.
On the application level, type associations in the current state make one sense: One can add a .TYPE EA to any file with any extension to make the double click on it open it in the wanted application - but only, if it supports it (e.g. by type associations in a WPS class) or if such a type association is defined.
The Extended Associations from XWP comes with great features:
1. Filters can be associated to file types. The WPS type assocs come before the WPS filter assocs.
2. Multiple filters can be associated to a type association.
3. Type associations can be arranged in a tree. Inheritance is supported.
Unfortunately it is not very stable anymore, since it was bundled with Turbo Folders. It leads to unpopulated folders, missing object icons and WPS traps. Work has to be done to really use it.
The past has shown that associations, defined per WPS classes, lead to problems sooner or later. These classes should be uninstalled, if possible. (A popular example is the class that the Acrobat Reader 3 installs for the .pdf filter.) Together with XWP's Extended Associations, but with increased stability, the WPS associations could be made much more convenient.
