scmJS docs

Command

True when the player has at least, at most or exactly the number of units of the type anywhere on the map. Blizzard's melee maps carry the standard defeat trigger, a player who commands no buildings loses:

Condition 2 · Command(Player, Unit, Comparison, Amount);

Argument Takes Stored in the condition
Player a player or group bytes 4–7
Unit a unit type, or one of the unit classes bytes 12–13
Comparison At least, At most or Exactly byte 14
Amount a whole number, 0 to 4,294,967,295 bytes 8–11
Command("Current Player", "Buildings", At most, 0);