Commander checksum byte. If the default commander is changed, a new checksum
will be calculated and inserted by the elite-checksum.py script.
The offset of this byte within a saved commander file is also shown (it's at
.CHKIF _SNG45 OR _SOURCE_DISCEQUB&03\ The checksum value for the default commander, #75ELIF _EXECUTIVEEQUB&3F\ The checksum value for the maxed-out default\ commander, #75ENDIF