The Half Relocation check box lets you determine whether PC-DMIS performs a FULL RELOCATION (FULL LEAPFROG) operation (if not selected) or performs a PARTIAL RELOCATION (PARTIAL LEAPFROG) operation (if selected).
Relocation refers to moving the portable measuring machine to a new location.
Doing a full relocation (clearing this check box) means you would need to measure something before you move the portable machine and then remeasure some or all of those items after moving the machine. Remeasuring allows PC-DMIS to determine the new location of the machine.
A half relocation (selecting this check box) means you move the portable machine first and then measure the datum features.