[ODE] ODE 2D?

[Gabriel Gambetta]

What's the best way to use ODE to do a 2D simulation?

The obvious answer I come up with is "use Z = 0 everywhere", but is that
enough? I mean, I'm afraid the simulation process (about which I'm
blissfuly ignorant) could introduce rounding problems or other problems
which could cause Z to become nonzero and accumulate and...

In a word - do I set Z = 0 initially and be happy, or should I keep
setting Z = 0 in positions, forces, velocities, etc?

	--Gabriel