Currently it's not possible to do a same day, i.e. to end of day loan. We're working on implementing such a circ rule.
Scenario is this: borrower checksout item return date is today ( i.e. midnight today ). Seems a logical requirement for ceryain collection. Logically its a day loan of length 0 but we have code currently forbidding that
It looks like this is still not possible. When putting 1 as a loan period, it will be the end of the next (opening) day. There is no way to set up an 'end of the same day' loan period.