Sacristan 

The sacristan is a lay person who “diligently arranges the liturgical books, the vestments, and other things that are necessary for the celebration of Mass” (GIRM, no. 105a). Working from the sacristy, he or she should be welltrained in the complexities of the liturgical actions, as well as those of special Masses or those of greater solemnity, so as to make appropriate provisions.