drive letter in file name

Going thru 4.0D and 5.0a library code, I do not see any provision for
drive letter in a filename.  For example, if I have a file
"/umb/why/d/theydo.this" on drive D, I should be able to specify
something like:


Furthermore, it appears that Microsoft and Netscape have different
syntax for dealing with this.  Is there a convention for this, and
corresponding code?

(Of course, this problem didn't show up on my UNIX system.  It's that
other $&*#)_%$$$!!* delivery platform that requires it.)

--Rick Kwan