[TUHS] Why does refer(1) have no database field for "edition"?.

[Douglas McIlroy]

Another issue I have run into is recursion, when a reference includes
another reference. This comes up in various forms:
     Also published as ...
     Errata available at ...
     Summarized [or reviewed] in ...
     Preprint available at ...
Often such a reference takes the form of a URL or a page in a journal
or in a proceedings. This can be most succinctly placed in situ --
formatted consistently with other references. If the reference
identifies an alternate mode of publication, it may lack %A or %T
fields.

Partial proposal. a %O field may contain a reference, with no further
recursion, The contained reference will be formatted in line in the %O
text unless references are accumulated and the  contained reference is
not unique.

Doug