string mixin reference

[O.F.]

Have string mixins been removed from the language reference? I can't seem to find any mentioning of it at all, other than on the newsgroups and for some of the phobos 2 modules.

In the latter case, it's pretty confusing for newcomers, as the library documentation shows how something works by using a construct that haven't been explained anywhere. It might also cause confusion over things like sort!("a < b"), which can appear magical if you don't know about string mixins.