[jjuran]

I hate to disappoint you, but the canonical way to clear a 68K address register is `SUBA.L An,An`. My asm-coded replacement for the Metrowerks code resource runtime uses it:

<https://github.com/jjuran/metamage_1/blob/master/mac/toolcha...>

[aruggirello]

Oops, you're right. I forgot stuff like `MOVE.L #0,Dn` is restricted to data registers. So this must be the way to go, every time a NULL pointer is needed...