COPY copies the image in buffer 'source' to the buffer 'dest'. The header
associated with the source image is also copied. NOTE THAT THE DESTINATION
BUFFER COMES FIRST ON THE COMMAND LINE! The syntax of the copy command is:
The related command, WINDOW, is used to trim (``crop'') an image or spectrum.
If you copy wavelength-calibrated spectra, you should copy the entire spectrum. You should not use BOX= with wavelength-calibrated spectra. If you do, the wavelength scale of the spectrum after the COPY could end up incorrect.