PEN Quick Start - Checksumming Files
For files that exist both locally and in the Project Warehouse (black files), the checksum is what the PEN tool uses to determine whether or not the file in your local directory matches the file in the Project Warehouse.
If the checksum of the local file does not match the checksum of the file in the Project Warehouse, the file will turn red instead of black.
You can perform a checksum on a file at any time.
Select the file in the left panel, right click, and select “Checksum” from the menu.