Properties Handlers Not Identified by FileMeta
Looking at the customizable profiles pane in FileMeta, you can see that the properties of other non-Windows handlers can be mapped by FileMeta, such as those of the Icaros codec and Zip files.
There is a tool called CBX Shell which displays in infotips a count of compressed objects in rar/zip files, but that does not appear in the FileMeta pane.
I wonder if it is possible to register the CBX Shell handler (9E6ECB90-5A61-42BD-B851-D3297D9C7F39) or others as customizable properties in FileMeta, since the CBX Shell handler is not listed in the FileMeta manager.
I had a quick look at the source code for CBXShell. The reason why it does not show up in the Association Manager is that it does not define a property handler. It does its work using thumbnail and infotip handlers, and so does not conflict or interact with anything that File Meta does (with the exception of infotips, where CBXShell will win, as it overrides the standard infotip handler that reads the infotip registry entries set up by File Meta).
I imagine that the other programs you mention do set up property handlers, and therefore appear in the Association Manager, along with the standard Microsoft provided handlers.
Dijji