What exactly is a Stance?

[FallenHero]

Lots of powers have "Martial, Stance" as keywords, but I've combed my PHB (and the Compendium) and can't find a definition for Stance.

Can you have more than one Stance active at a time?
Does a Stance go away if you move?
Are there any powers that have different effects depending on a Stance?

If there's a page I've missed, please feel free to point me to it so I can look it up for next time. Thanks.

 

[Danceofmasks]

PHB p55

Lasts until end of encounter, or until you use another stance.

 

[Tony Vargas]

The bland list of keywords in the introduction to powers fools you. Most of them are strictly cosmetic, ooh, the 'fire' keyword does fire damge... and that lulls you into skimming them.

But a few, like Stance, have actual, vital mechanics hidden in them.

Stances are really pretty cool, all martial classes should get a few, I think. You could even bring back 'fighting defensively' as a universeally availabe 'stance,' if you wanted...