Does anyone know what these holes are for in the roof rails?

[DarkPony]

Trying to figure out what these are for. I have a set of flat crossbars I’d like to see if I could make fit until I get a full rack. Any ideas?

 

[kophoto4x4]

I could be wrong but they might be for those cross bars to lock into?

 

[Riviera]

Have you tried moving the x-bars? I'm just guessing since there's no obvious reason for the holes but I wonder if those holes have something to do with the cross bars only allowed to be placed in a few locations and some pin in the cross bars has to drop in the holes? So in other words there would be holes underneath the current cross bar location too.