Nodes of different colours represent the following:
Solid arrows point from a submodule to the (sub)module which it is
descended from. Dashed arrows point from a module or program unit to
modules which it uses.
Need program statement for FORD
Reproduces data of:
* Figure 3 in https://agupubs.onlinelibrary.wiley.com/doi/10.1029/2008JA013384
* Figure 2 in Fang 2010
Nodes of different colours represent the following:
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.