>I have noticed that addbs() does not add a backslash if given an empty path. I'd expect a backslash even in that case, creating a reference to the root! I can't imagine that this was done by design. Who's at vault?

empty to empty, it is correct.

within VFP an "empty path" is "the default directory",
and ADDBS() must preserve it.

? FILETOSTR("filename.filetype")
* this must to be equal
? FILETOSTR(ADDBS(JUSTPATH("filename.filetype"))+JUSTFNAME("filename.filetype"))