Quick Attributes Question.

I making Mods to My Merc Air Ele's Build today;
And the Game would not let me buff her abouve 12; it's not that I was out of Points there was simply no up arrow at all; and I know I've bumped into this before.

I know I've seen builds with Attributes as high as 16? Am I right in thinking the only way you can push a stat beyond 12 is Runes, and to 16 is Superior Runes?

Your thoughts,
Thanks BB.

12 without runes.

13 with headpiece (stacking) of that attribute.

14/15/16 with a minor/major/superior rune of that attribute.

Thanks Much Alay. : ) BB.