A: you can call a violation anytime there is no stall count. E.g. if there is no marker in zone defense)
B: you can call a violation only if there was a stall count and then there is no stall count after a marking infraction was called. E.g. Stalling 1, 2 – “Fast Count” – [prolonged silence from the marker] – “violation”.
This rule states that “Instead of calling a marking infraction, the thrower may call a marking violation and stop play if there is no stall count”.
This means that if, for example:
the marker is straddling the thrower, and
the marker is not counting the stall count,
instead of calling a straddle infraction (which will have no impact on the stall count, because there is none), the thrower can call a violation and stop play.