- Not available on that edition (the reason is in the tooltip)
- Depends on the setting, your class or another addon (details in the tooltip)
What it does
Checks how many marked units are known.
Why you might use it
Count known marks, optionally filtering friendly or enemy units. Available on Classic and TBC; unavailable on Retail and Forever. A known unit that moves out of reach can remain counted until the marker table is refreshed.
Example
the number of marked units is equal to 2
Settings
What each setting in the condition editor means, from the game's own help.
Counts the marked units Rotation Master knows of. It finds them on your target, focus, mouseover, nameplates, group members and their targets, bosses and arena opponents each time a mark changes, so a marked unit you cannot reach right now still counts until the mark is seen to be gone or you leave the area. Count every marked unit, only enemies, or only friendly units. If a marker cannot be read, or a unit's hostility is unknown for the filter you chose, the condition is unavailable, also under NOT. A unit carries at most one mark, so the count is never more than eight.
Operator - How to compare Raid Mark Count with the Value value. This comparison uses basic mathematical comparison operations.
Value - A number from 0 to 8: there are eight marks, and a unit carries at most one.