David Greer wrote:

I think you are confusing MAC's and DOS here. My recollection is that DOS stored filenames in 11 contiguous characters without the ".". It being assumed that the last three characters were the extension.

No. It is an 8-byte field and a 3-byte field. The fact that these fields are adjacent to each other in the structure does not transform them into a single 11-byte field. Note that when the name is less than 8 characters, the name field is padded with NULLs, and the extension remains stored in the same place (bytes 9-11, relative to the first byte of the name).

Macintoshes did / do store the extension as a separate entity in the structure.

Macs don't have any concept of extensions whatsoever. File type information is stored completely separately and has nothing at all to do with filenames. The system shell (and most applications) do not give users the ability to view or alter the four-byte file-type codes. -- David