This group of topics explains how mapping routines are used in
the flow editor.
Where to use mapping routines
A mapping routine can be referenced from: (a) an Assign node; or
(b) from the input terminal or an output terminal of
most types of Invoke nodes.
How mapping routines are accessed
A reference to a mapping routine includes (a) the name of the mapping
routine, and (b) the name of the mapping file in which the mapping
routine is located.