Who knew there was such a thing? I guess it makes sense if you take a vow of silence.

Monastic Sign Language

A language of Vatican State

ISO/DIS 639-3: mzg

Population	No estimate available.
Region	Monastic communities, especially in Europe.
Dialects	Anglo-Saxon Monastic Sign Language, Augustinian Sign Language, Benedictine Sign Language, Cistercian Sign Language, Trappist Sign Language.
Classification	Sign language
Language use	A second-language means of communicating while maintaining vows of silence. Not a deaf sign language.
Comments	Second language only.