[Groff] Reformatting material

[Denis M. Wilson]

Relating to a recent thread, I've long searched for a way to
reformat the same material three times, on each pass using
information gleaned from earlier passes. Only the final pass
would produce output. Examples of this could be balancing
multi-column output, or avoiding ragged bottoms.

Diverting will not do as some undoable formatting is
performed on them, for example vertical spacing is set
in concrete. A further idea was to write the material to a
termporary file, but I could not see a way to do this.

Any tried this or have ideas?

Denis