Encyclopedia
Sacristy
Riznitsa (diaconicon) - a room located in the southern part of the altar or beneath the altar, intended for storing clergy vestments, liturgical items, and church furnishings
Source: "SP 31-103-99. Buildings, Structures, and Complexes of Orthodox Churches"
(adopted by the Decree of the Russian Federal Service for Supervision of Construction dated December 27, 1999, No. 92)