Oddly Shaped Aluminum Channel

Hi, everyone.

I’ve been trying to find the name for a type of punched metal channel that looks like a u-channel but it has a flange-like component jutting out from one side. It looks like a question mark without the point. Apparently it was part of a KOP a while back. Anyone have any ideas?

Thanks!

Sounds like the kitbot rail (PN 217-0437).