GEDitCom, and perhaps other programs, have recently added the
custom tag _UMR for family relationships in which a child was
produced but no marriage occurred, so the titles HUSB/WIFE are
inappropriate or most certainly no factual.
This tag is displayed as
and if so formatted converts the headings/tags for the HUSB/WIFE
within that "family" unit to FATHER and MOTHER (although it
doesn't change the gedcom files notations).
The tag is removed if a MARR occurs and would not be reflected
as _UMR N.