How is this done? (glass balustrade)

[several]

See attached image, I want to know how to achieve this. Where is the glass fixed?

I know you can get channel for frameless glass balustrade's but I've seen a few examples like this where the glass does not appear to fit in a channel, but it's not clear where the fixings are.

The plasterboard is so thin on the front, it's hard to imagine it's covering stand off fixings.

 

[pilsbury]

Looks to me like a stepped channel where the cut stepped glass slots into.