[erlang-questions] io:request/2 documentation?

[jm]

Reading up on Leex and Yeec at 
http://hopper.squarespace.com/blog/2008/5/29/leex-and-yecc.html and it 
makes use of io:request/2 in one example. Yet there doesn't appear to 
any documentation for io:request/2. Is this another undocumented OTP 
function for insiders? Can this be used with a socket generated by 
gen_tcp? (I'm guessing not) and, if not, is there a suitable substitute 
for use with a tcp socket?

Thanks,
Jeff.