I don't know what we'll call it, but I was told not long after I'd
set up a dating system for photographs using 1900-09, 1910-19 etc that
the decade REALLY started on 1 and went to 10, 11-20, etc. I actually
saw something to that affect, but decided I'd do it my way.
Diane Brenner, Anchorage Museum Archivist