why both works for ATF22V10C

[quantrpeter]

Why these pins in gal files also work for ATF22V10C

CLK  A B NC NC NC NC NC NC NC NC NC GND
NC    NC NC NC NC NC NC NC NC Z Y  VCC

and

CLK  A  B  NC  NC  NC  NC  NC  NC  NC  NC  GND
VCC  Y  Z  NC  NC  NC  NC  NC  NC  NC  NC  NC

thanks
Peter