scmJS docs

Run AI Script

Starts an AI script for the player, which is normally a computer player: the custom-level scripts that make it play a normal game, or one of the small scripts that change its behaviour.

Action 15 · Run AI Script(Script);

Argument Takes Stored in the action
Script an AI script, stored as its four-letter code bytes 20–23
Run AI Script("Terran Expansion Custom Level");