Explicit supply game

[Aetius]

Anybody knows by which priority the game system allocates supplies?
I am playing a Normandy campaign and the 30-strong supply units that land ashore have a range that covers some two or three divisions. They immediately disappear as soon as I change them out of travel mode, of course, and still leave many units unsupplied.
I believe to have noticed a pattern: units with low on ammo problems are supplied first, then the low on fuel ones, and only then the unavailable artillery.
The system also doesn’t seem to care much about proximity to the supply unit, as it seems that those who get the supplies are always the same (possibly due to the unit number on the database)?
I have checked the manual and I found nothing on the subject. Can anyone confirm if the above impressions I got are correct or not? It is important when you are fighting a campaign where the supplies are rationed.