I see the Wiki states for air unit "all withdrawn units will appear in the reinforcement pool with a "transit delay", preventing them being recommissioned until the delay has expired."
As I understand it does that also means the specific unit name of withdrawn unit becomes available again in the 'Select Unit Affiliation Details' section for reinforcements ?
While we are on this subject I would like to point out that some care should be taken to pick an appropriate name when selecting from the reinforcements as in some campaigns the unit naming function seems a bit confused. Of course that could just be me
I think your correct Ikey as I recall trying to make sure the names were correct when aircraft were returning to sector (after withdrawing to bomb New Guinea) back in June 42 campaign. That was a long time ago now though so it might just be an aging mans false memory.