CP/M directory entries

Is there any kind of sensible maximum limit for the number of directory entries that a CP/M disk may contain? Or did every vendor just do their own thing (probably!) and it's preferable to just keep parsing from the start of the directory area until either the end of the media is reached, or a location identified as file data by a previous entry is encountered? And, related to that, if the directory area of a CP/M disk spans multiple tracks, was there a standard for whether it iterated head-first (in the event of media with multiple heads) or cylinder-first? Or does code have to cope with both possibilities? I'm just pulling some data off some QX-10 floppies (none of which seem to take up more than a track for the directory area), but it seems like a good idea to make it as generic as possible. cheers Jules