Library whining
If something is a rather large index, and is shelved with the microfilm because it is helpful in using one of the microfilm collections (but is not actually an index to that collection), there needs to be a distinction made in the catalog. The call number shows that the book is microfilm (FLM Z2002), which made me think that it was an actual reel of microfilm. It is not. It is a book, which is stored on a cart near that shelf of microfilm. I spent half an hour looking for this thing last week.