When challenging an irc @op action, or voting about removing @op power from someone, said @op may not veto. A single person who got affected by the action may not start the vote, or veto. Violating this rule decides the most negative outcome of the vote for the violator.
divVerent
VETOED
is an unbalanced system of voting which in any other case does not apply this way, specifically regarding removal of core team priviledges or any other such situations. (by Samual)