a   book
b   archive/manuscript
c   music score
e   map

g   video recording
h   e-book 
i    Internet site
j   CD(Sound)
k  graphic media
m  computer file

n  record/cassette/tape
o  kit
p  projected media
r  3-D object

s  serial
t  diagnostic test
x k-12 textbook
y e-audiobook
z  other/misc

Last Update: November 3, 2008