Does anybody knows any details about this file?
Is it for example safe to exclude this file from SVN? I would say that it should not be problem because when I delete this file, I can still load the XFL and the file is created again on the next save.
it seems that SymDepend.cache is used to keep track of all .xml files modification dates. Flash CS5 checks it upon saving to determine which files have to be resaved, deleting the cache makes Flash CS5 resave the whole library at next save.