Nodes of different colours represent the following:
Solid arrows point from a file to a file which it depends on. A file
is dependent upon another if the latter must be compiled before the former
can be.
program volatile_doctestuse vecfor_RPPtype(vector)::pt(0:2)pt(1)=2*ex+3*eypt(2)=expt(0)=pt(1).ortho.pt(2)print"(3(F3.1,1X))",abs(pt(0)%x),abs(pt(0)%y),abs(pt(0)%z)endprogram volatile_doctest