extra "L" bracket for p6n (msi-7350)

There is a "L" bracket that came with my p6n mb & the various docs
don't even show it in the parts pictures. Wondering what it is
to be used for. There is a bracket for the usb & another bracket
for the firewire.

The "L" bracket appears to help hold something or other & have
many serated retangular holes in the bracket for ventilation(?).
The bracket is like an end bracket but also have a horizontal
plate attached to the bracket. __
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Just curious & would like another piece of useless info......