We don't need to ask to Apple.
We may set our system to use ISO 8601. As far as I remember, it would accept most of your proposals.
set maybe to "2015/5/6"
log "01, " & date maybe
log short date string of (date maybe)
set maybe to "2015-5-6"
log "02, " & date maybe
log short date string of (date maybe)
try
set maybe to "2015/5"
log "03, " & date maybe
log short date string of (date maybe)
end try
set maybe to "2015 5/6"
log "04, " & date maybe
log short date string of (date maybe)
set maybe to "15-5-6"
log "05, " & date maybe -- bad maybe
log short date string of (date maybe)
set maybe to "15/5/6"
log "05, " & date maybe -- bad maybe
log short date string of (date maybe)
set maybe to "2015/5/6 10:11"
log "06, " & date maybe
log short date string of (date maybe)
set maybe to "2015-5-6 11:12:13"
log "07, " & date maybe
log short date string of (date maybe)
set maybe to "11:12:13"
log "08, " & date maybe
log short date string of (date maybe)
Here with yyyy/mm/dd hh:mm:ss as default for the two first formats which we may define in pref System it return :
(*01, mercredi 6 mai 2015 00:00:00*)
(*2015/05/06*)
(*02, mercredi 6 mai 2015 00:00:00*)
(*2015/05/06*)
(*04, mercredi 6 mai 2015 00:00:00*)
(*2015/05/06*)
(*05, lundi 15 mai 6 00:00:00*)
(*6/05/15*)
(*05, lundi 15 mai 6 00:00:00*)
(*6/05/15*)
(*06, mercredi 6 mai 2015 10:11:00*)
(*2015/05/06*)
(*07, mercredi 6 mai 2015 11:12:13*)
(*2015/05/06*)
(*08, jeudi 20 août 2015 11:12:13*)
(*2015/08/20*)
Yvan KOENIG running Yosemite 10.10.5 in French (VALLAURIS, France) jeudi 20 août 2015 21:13:59