man smb.conf (entry "mangled names") says "The first three alphanumeric
characters of the final extension are preserved, forced to upper case and appear
as the extension of the mangled name. The final extension is defined as that
part of the original filename after the rightmost dot."

Samba 3.0.7, at least with hash2 mangling, does not implement this -- so any
mangled *.flac files on a Linux server, such as "Foo?.flac" appear extensionless
on a Windows 2000 client, rather than as the still-usable "*.FLA". The problem
is in name_map() in mangle_hash2.c, where the variable 'dot_p' is used both to
delimit the extension and to record whether the extension is already
3-char-ASCII-kosher. In particular, on line 569 it tries to use dot_p to mangle
a non-kosher extension, but in the non-kosher case dot_p will already have been
zeroed by line 537 or 541. A fix would be to invent a new variable
"should_mangle_whole_name" (or some pithier term), clear it by default, set it
on lines 537 and 541, and test on it (rather than dot_p) at line 560.