[NTG-context] Where is ifforwardreference defined?

[Sanjoy Mahajan]

> grep -r ifforwardreference .

That finds only the \newif and uses of the new if.  To find the
algorithm, you want

  egrep -r 'forwardreference(false|true)' .

because the assignments are done by \forwardreferencetrue and
\forwardreferencefalse (a property of the TeX macro language, so not
specific not ConTeXt).

-Sanjoy

`Not all those who wander are lost.' (J.R.R. Tolkien)