Level 2 Help for AVERAGE

INP specifies the input data sets.  Up to 48 are allowed.

The SIZE parameter may be used when only a sub-region of each image is to
be concatenated; it has the format SIZE=(SL,SS,NL,NS), where the parameters
are starting line, starting sample, number of lines, and number of samples,
respectively.  SIZE=(1,1,10,10), for example, will cause AVERAGE to only look
at the first ten samples of each of the first ten lines in each image, when
performing the concatenation. 

INTEGER - Starting line (see SIZE)

INTEGER - Starting sample (see SIZE)

INTEGER - Number of lines (see SIZE)

INTEGER - Number of samples (see SIZE)