Gopher item types

Item types are described in gopher menus by a single number or
(case specific) letter and act as hints to the client to tell it
how to handle a specific media type in a menu, analogous to a MIME
type. Every client necessarily must understand itemtypes 0 and 1.
All known clients understand item types 0 through 9, g, and s, and
all but the very oldest also understand file-types h and i.

    0 = plain text file
    1 = directory menu listing
    2 = CSO search query
    3 = error message
    4 = BinHex encoded text file
    5 = binary archive file
    6 = UUEncoded text file
    7 = search engine query
    8 = telnet session pointer
    9 = binary file
    g = GIF image
    h = HTML file
    i = informational message
    I = Image file of unspecified format. Client decides how to
    display. Often used for JPEG images.
    s = Audio file format, primarily a WAV file
    T = tn3270 session pointer

A list of additional file-type definitions has continued to evolve
over time, with some clients supporting them and others not. As
such, many servers assign the generic 9 to every binary file,
hoping that the client's computer will be able to correctly process
the file.