Hanging this type of mirror

[smp50]

How do I work with this mirror, bearing two of these along its top edge:

Clearly something on the wall is meant to slot in there but do I just use anything like a thick screw, or is there a special wall-side fitting that I need to use?

Thanks

 

[honda]

I've always understood that the idea behind these is to prevent whatever they are fitted to from slipping hence the serrations. I would hang it with a suitable nail/screw bearing in mind it's weight if it's a heavy mirror.

 

[foxhole]

Picture pin in the wall , serrations allow adjustment to level.