Vent Partial End Caps is a parameter of the remove faces operation. It creates vents along certain end caps which creates additional faces. The following figure illustrates the effect of removing the highlighted face.
By default, the Vent Partial Blend Caps parameter is False, which results in the following solid.
Changing Vent Partial Blend Caps to True results in two additional vent faces as shown in the following figure. In many cases, this parameter has little or no effect.