Looking at biblatex again, I note they have a normalize data form that
seems effectively to be a subset of EDTF; e.g. ISO/W3C date
representations, plus compound/range dates. E.g.:
2002-01/2002-02 —> 01/2002–02/2002 (short form) and January
2002–February 2002 (long form)
From the docs:
“2.3.8 Date Speciﬁcations
The date ﬁelds date, origdate, eventdate, and urldate require a date speciﬁ-
cation in yyyy-mm-dd format. Date ranges are given as yyyy-mm-dd/yyyy-mm-dd.
Partial dates are valid provided that date components are omitted at
the end only.
You may specify an open ended date range by giving the range separator and
omitting the end date (e. g., yyyy/). See table 2 for some examples of
speciﬁcations and the formatted date autmatically generated by biblatex. The
formatted date is language speciﬁc and will be adapted automatically.
If there is
no date ﬁeld in an entry, biblatex will also consider the ﬁelds year and month
for backwards compatibility with traditional BibTeX. Style author
should note that
date ﬁelds like date or origdate are only available in the bib ﬁle.
All dates are
parsed and dissected into their components as the bib ﬁle is processed. The date
components are made available to styles by way of the special ﬁelds discussed in
§ 126.96.36.199. See this section and table 7 on page 126 for further information”