"imap" argument of netCDF function "ncvargetg"

Dear netcdfgroup:

I'm using the function "ncvargetg" to read a two-dimensional array of variables 
from a netCDF file.  Under certain circumstances, I'd like to invert th order 
of the columns and/or rows of that array.  I assume that can be done by 
manipulating the "imap" argument to "ncvargetg", but I'm not sure how.  Neither 
the netCDF manual's explanation of "imap" and "ncvargetg" nor the example of 
their use given there make any sense.  If anyone knows how to use "ncvargetg" 
and "imap", I'd very much like to hear from him or her.

Thanks for your help.

David Simas
Atmospheric Sciences Department
Oregon State University