Not if it has a purge!
I think Jeff is on to something... Let's take our average diver, call him Ace. He's just starting out diving and he's not made of money, so he buys things piece by piece.
1) regs, doubles, and BP/W
2) can light
3) wetnotes, SMB, spool
4) drysuit and jet fins
und so weiter...
At what point does he become DIR? After he buys the can light? Maybe after the SMB/spool?
or maybe it's a mindset that motivates his gear choices?
What if Ace doesn't want to dive in caves or wrecks, and doesn't want to get into deco? Does it matter which side his can light is on?