Sam Spade wrote:


I don't want to whip this puppy to death, but if ACME TRACON tells PDQ
VFR tower to "release N1234C at 24 minutes past the hour, void after 27
past the hour"


They don't give a release like that to a tower. That's FSS stuff only.
The tower will be given the release with any restrictions such as
altitude and/or heading.



what possible separation duties is the tower performing
other than to comply with the release time, which assures the separation
the TRACON is providing will, in fact, happen.


The release will be given and the tower has to separate the departure(s)
from any arrivals already talking to the tower. The tower has to ensure
initial separation from successive departures, especially diverging
runways where the departures then have to turn back toward each other to
get to their radar assigned headings.