one more secret, of many...
learn that many makers of things use codes for dates
and the codes can be simple (none stated by you)
like this, Julian dates, or reverse , work weeks, coded.
my company long ago, home based in Europe used 10 month calendars for month and work weeks, yah tricky.
The date codes are also sometimes encrypted with very complex rules (endless types) and mostly hopeless trying.
history is clear as day why: (lived it)
In the 90s many buyers sued, the makers of chips. (intel and others)
said the chips were old and last years model, (all lies)
but the chip makers lost, even with lies told.(courts sux)
what the chip makers did was encrypt the dates.
and for extra , safety only marked them , only when sold in bulk.
(laser marked in fact).
so finding the code is hard, or very simple but not stated by you your code. why skip the obvious. not asking serial. ok./
some codes are 4 digit and simple
like 4587, work week 45 year 1987
or the reverse.
or julian dates. 4 digit.
true julian dates go back to on January 1, 4713 BC
but in practice we use simple Julian dates.
so 1215 is (shift #1) August.3 (no leap) (work shift)
its fun to try to decode them, and best done with more examples.
non stated sadly.