I've been wondering about this for sometime, and I was wondering:
If a person uses:
Glyph of concentration
Mantra of concentration
Mantra of resolve
And then their opponent knocks them down when they are using a skill or spell, do they stand back up and resume casting or is it interrupted?
Does knockdown by-pass anti-interrupt spells/skills?
Waylayer Brixt
rii
Its not an interrupt, its a kd... so concentration, concentration, and resolve do nothing. balanced stance, doylak signet, and... erm, i think thats it stop kd. If you get knocked down whilst casting though its the same as an interrupt. Definately true for resolve (tested) but not sure about the other two.
Rajamic
Indeed, knockdown is separate but more effective than simple interrupts. It requires a separate set of skills to protect yourself from it.
smurfhunter
ultimate uninteruptable dude: glyph of concentration, balanced stance. if only the ghostly was like that when capping on the altar 
rii
....just interrupt the glyph.... it would be cool if glyphs had fractional/non-existent times.... theyve always seemed to like links in a chain, which allows eles to throw out a load of stuff for less/more effectively. Therefore, 1s casting times makes it seem ungainly.