There is of course a fourth, highly classified method called real-time visualisation. It was taught by my aircrew survival instructor and had many years fun teaching it too trainee aircrew.
Orient map.
Find small tree or bush (no taller than yourself).
Stand to the left of the tree/bush, with map still correctly oriented.
Reach out with right hand and grip tree/bush firmly with right hand.
Shake tree/bush whilst looking at map.
Look for tree/bush shaking on map.
Spend next five minutes rolling around laughing at 20 aircrew shaking bushes in a field...

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Gordon Brown saying I got the country into it's current economic mess so I'll get us out of it is the same as Bomber Harris nipping over to Dresden and offering to repair a few windows.
Chaos, panic and disorder - my work here is done.
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