rat 1 Sections StandardLIB Doc
IF YOU CAN SEE THIS go to /sfa/Nuprl/Shared/Xindentation_hack_doc.html
Def q.den == 2of(q)

is mentioned by

Def a *q b == (a.numb.num)/(a.denb.den)[qmul]
Def a +q b == (a.numb.den+b.numa.den)/(a.denb.den)[qadd]
Def a =q b == a.numb.den=b.numa.den[eq_rat]

Try larger context: StandardLIB IF YOU CAN SEE THIS go to /sfa/Nuprl/Shared/Xindentation_hack_doc.html

rat 1 Sections StandardLIB Doc