Nodes of different colours represent the following:
Module Graph
Solid arrows point from a parent (sub)module to the submodule which is
descended from it. Dashed arrows point from a module being used to the
module using it.
Type Graph
Solid arrows point from one derived type to another which extends
(inherits from) it. Dashed arrows point from a derived type to another
type containing it as a components, with a label listing the name(s) of
said component(s).
Call Graph
Solid arrows point from a procedure to one which it calls. Dashed
arrows point from an interface to procedures which implement that interface.
This could include the module procedures in a generic interface or the
implementation in a submodule of an interface in a parent module.