.OUTPUT FILE: COP001 or COP001@003
[Enter the file that will contain the copy.
If the filename is COP001@003, SPIDER will copy the input
file into the stack file with name COP001 at the third
position. If the stack file COP001 doesn't exist, SPIDER
will creat a new stack file with a stack file header and
the input image at the 3rd position. The black images will
be filled in front of this image(001 and 002).]