Originally Posted by gatorbird

In the case of FLL, we're never on an RNAV departure intially, we're simply on an assigned heading. Once you are cleared to an enroute fix you are then considered on the SID. I've heard it termed before as "cleared to __ to join the DP".

Maybe someone else has an obscure rule or side letter on the issue, but that's how our POI and the controlling ATC personnel view it. I'll side with them.