PUM and PS_MAINTENANCE_LOG - FIXOPRID value requirement?

We have recently upgraded to PS 9.2 and so are new to the PUM maintenance methodology.  We have applied PI 17 to our environments using PUM and though successful, had some unexpected results.  More specifically, the change package defined using PUM/PI 17 included not only the objects associated with Tax Update 16-B (which we expected) but also the object associated with Tax Update 16-A (we did not expect this, as our target database already included TU 16A).  Our research in trying to understand why TU 16A was included in the change package has led us to the PS_MAINTENANCE_LOG and some