Quoted from mattosborn:
This is a RAM... there's no checksum matching that needs to be done. The code may run corruption checks on certain sections of RAM on boot, but I highly doubt there is any checksumming going on.
WMS games run a checksum on their nvram contents, sometimes down to the individual adjustment/audit, sometimes on groups of adjustments. They've been doing this back into the system 7 era.
If WPC does it the same way as system 11, the adjustments get one checksum, and each audit (which includes the hstd, even though it's not an 'audit') has their own. If the checksum doesn't match on an audit, when you are scrolling through them, it puts 'Error' on the display.
I guess it could be called a check byte? Integrity byte?