In reply to Toerag:
> Which got me thinking, will 'grid to mag...add; mag to grid...get rid' change? Does that apply in countries on the other side of the world now?
It's why I've never liked that mnemonic. Not to mention that I can never remember what the mnemonic is supposed to mean...
I've always just remembered whether MN is W or E of GN, locally, and move the compass capsule accordingly when taking a bearing from map or ground. It works universally.
The 'adding/subtracting' bit is only actual arithmetic if you're quoting a bearing to someone else. If you're navigating on your own, you don't need to pay any attention to the actual numbers, as long as you set the compass correctly; just rotate the capsule by the relevant amount.
ps. try ignoring GMA if you're in NZ...
Post edited at 14:30