"rails". the horizontal bit is a "rail".

the installer of the handles had a jig to locate the hole/drill locations. they followed the inside edges of the panel, and that means the hole locations are related to the top of that rail.

for some unknown reason (possession by a psychopathic demon, perhaps) someone made a pair of cabinet doors with bottom rails of different dimension. or, or, they installed the door upside down, and the top rails are a different dimension.

so much going on there. look at the right "stile" (the vertical bit of wood framing the panel sides). It's monstrously wider than the meeting stile (the one with the handle).

I may need to drive over there and perform an exorcism, carpentry-wise