When a Gaussian binary checkpoint file (*.chk) is opened by #APPNAME#, the corresponding formatted checkpoint file (*.fch or *.fchk) is what is actually read. The formatted file is created from the binary file using Gaussian's formchk utility. The file is stored with a unique, arbitrary name in a temporary scratch directory that is difficult to access and is deleted when #APPNAME# is exited.
To save such a temporary formatted checkpoint file to a non-scratch directory for later use, select Save Temp Files from the File menu. By default, the saved formatted checkpoint file will have the same base name and path as the parent checkpoint file.