Where are the semantics of shared defined?

[rsw0x via Digitalmars-d]

On Friday, 14 August 2015 at 12:43:26 UTC, thedeemon wrote:
> Anrei's TDPL book spent a lot of words on shared (and this book 
> had kind-of-a-spec reputation), but I don't know how much of it 
> is relevant now.

I know for a fact that a lot of the things related to shared in 
TDPL aren't implemented or considered anymore.

Is it really not documented anywhere of what shared actually does 
currently?
This is ridiculous.