Level 2 Help for INSERT3D

The first input is the 3-D file. The second input is 
the 2-D file containing the band to be inserted.

Contains the result of the second input being written
into the first. The inputs are always left unchanged 
by this operation unless 'UPDATE is specified in which
case the primary input is written into and the output,
if present, is ignored.

The band number of the band to be overwritten or inserted 
behind, depending on the keyword, 'OVER.

Will cause the second input to be overwritten on the selected
band of the first input. Inserting the second file behind the
indicated band of the first file is the default. In this case, 
the output file will have a band count greater by one than 
primary input.

Will cause the primary input to recieve the band rather than
the output. 'UPDATE implies 'OVER, that is, in 'UPDATE mode
the new band must overwrite its existing counterpart.