>Hi everybody,
>
>I'm trying to investigate strange problem. If I run this command in command window: "DO MAPREF", it fails with "Data type mismatch" error. Debug shows "Source is unavailable". If I change it to DO MAPREF.APP, it runs my correct file and I don't see an error. The same if I DO MAPREF.PRG. So, I thought, may be I have Mapref.exe somewhere, so I did ?FULLPATH("MAPREF.EXE") and it returned a path, while FILE("MAPREF.EXE") returned .f. and Windows Explorer also don't show this file. I've checked HELP file on FULLPATH() in VFP6, but this "feature" is not mentioned here.
>
>What is it: Help omission or bug/feature in FULLPATH() behavior? And why am I seeing this strange problem with error?

Yes, it's in the help:
"If the file can't be located in the MS-DOS path, a path and the file name are returned as if the file had been found in the current default directory".