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(1:2)real(R8P)::apt(1)=expt(2)=2*exa=pt(1)%angle(pt(2))print"(F3.1)",aendprogram volatile_doctest