core.stdc.config

[Craig Dillabaugh]

So, there is a module core.stdc.config (referenced here):
http://dlang.org/interfaceToC.html

That is presumably part of the D Standard library.  I am curious 
to know why no mention of this library is included at:

http://dlang.org/phobos/index.html

Is it not part of Phobos? Are there standard modules in D that 
are not included in Phobos?  If so, where would one find the list 
of these modules.