>Is the MARC Bibliographic format designed to allow the encoding of
>material type

No.

LDR/06 has the following values:

a = language material
c = notated music
d = manuscript music
e = cartographic material
f = manuscript cartographic
g = projected material (which kind in 008/33)
i = nonmusical sound recording
j = musical sound recording
k = two dimensional graphic material
m = computer file (now only data, games, and programs; with print
    electronic resources in "a")
o = kit
p = mixed material
r = three dimensional objects (i.e., realia)
t = manuscript language material

Older records have "m" for all electronic resources (aka computer
files), so there is no  consistency and no correspondence with
245$h[gmd].  The lumping of everything from slides to motion pictures,
videorecordings and overhead projectionables in "g"; and language
whether print or electronic in "a"; but manuscript languge having its
own code "t", makes the coding strange and largely useless.  Better go
with 245$h[gmd].

There are vacant letters, so things could be improved.  Numbers are also
available.

Using numbers with a one-to-one correspondance to gmds could be useful.

   __       __   J. McRee (Mac) Elrod ([log in to unmask])
  {__  |   /     Special Libraries Cataloguing   HTTP://www.slc.bc.ca/
  ___} |__ \__________________________________________________________