[topspin]

This is the opposite of what I understand: anode positive, cathode negative.

Google (and multiple other sources) confirm my understanding:

  an·ode /ˈanōd/ the positively charged electrode by which the electrons leave a device.
  cath·ode /ˈkaTHˌōd/ the negatively charged electrode by which electrons enter an electrical device.

[OnlyOneCannolo]

It depends on whether you're talking about electron flow or conventional current, because they're opposite each other. The original mnemonic is incomplete because it doesn't specify to which it refers.

[ultimape]

left hand side of the road, or right hand side of the road?

[topspin]

You've lost me.

[grzm]

Different domains have different conventions, regardless of what may be in a definitive reference.

[ultimape]

obligatory xkcd https://xkcd.com/567/