Releasable system
From ropewiki.com
A releasable system can mean two substantially different things depending on context.
A releasable rigging is a system where the rappel rope can be lowered after releasing the mechanism holding it in place.
A releasable anchor is a system where rigging and/or anchor material can be dropped to the bottom of the rappel without pulling down at least the rappel length worth of rope or retrieval cord.