EASA Post-flight duties/start of rest
 

It is not explicitly mentioned in PARTs, but I recall an EASA guidance or FAQ that mentioned that if the crew has no other duties after leaving the aircraft, the post-flight duties end and the rest period starts only when the crew is out of airside. Unfortunately, I cannot seem to find this info anymore, can somebody guide me to it?

Never seen it, but it's a common practice in my base for captains to delay check out for the entire crew only when we're out of the terminal.

I am aware of such practice (and I'm doing it myself), but I want to find the legal basis for that.