YYYYMMDD sorts very well chronologically, but YYYYDDMM would only be useful in a very specific set of circumstances (generously speaking I can only really think

YYYYMMDD sorts very well chronologically, but YYYYDDMM would only be useful in a very specific set of circumstances (generously speaking I can only really think of it being useful in cases where you have events that occur once a month on the same day, and for some reason it's more important to have those grouped together than to separate them by month). I suspect you misread and mistyped, but if not, I'd be really interested to hear cases where YYYYDDMM is actually practically useful!