Again, for those who use Keil's middleware - FAT frename function has a nasty bug: if new name contains path (for example "M:\name.txt") the whole string will be used as new name. In this particular case, file will be renamed to M:\name.txt - and now it's not accesible anymore since it contains forbidden characters ':' and '\'. Behaviour is completely wrong. If the path is specified, frename should copy old file to specified destination. In my case, I've created a wrapper function that corrects this issue, which I call instead of frename.
http://www.keil.com/support/man/docs/rlarm/rlarm_frename.htm
We this would be the difference between a "file name" and a "path name", or fully qualified path.
Not sure this qualifies as a bug, the documentation seems adequate, a gotcha perhaps?
With a path name your in the realm of a file move function.