MARC21-007: Reduction ratio range of microform
high reduction
Between 31:1 and 60:1.
c
low reduction
Less than 16:1 ratio.
a
normal reduction
Between 16:1 and 30:1.
b
reduction rate varies
Not all parts of the microform have the same reduction ratio.
v
ultra high reduction
Over 90:1.
e
unknown
Reduction ratio is not known.
u
very high reduction
Between 61:1 and 90:1.
d
Published