Certain actions have the 'concentrate' trait - e.g. Recall Knowledge, Demoralize, Cover Tracks, Sustain a Spell. I cannot for the life of me find an explanation of how it works in the Core RB.
On p. 630 we're told that 'an action with this trait requires a degree of mental concentration and discipline. Unless 'concentrate' is merely a flavour trait, that explanation is as helpful as the proverbial chocolate teapot.
