Locking

restrictions {
  locked = true
}

A locked item stays where it was put: it cannot be moved, dragged, swapped, dropped or placed, and it is taken out of the death drops instead of falling on the floor. A respawn trigger then hands it back.

An unlocked item behaves like any other item: a player may move it, drop it, or lose it on death. It still keeps its mark, so /uxmjoinitems clear finds it.

Related: Item files