The Typikon (Greek: τυπικόν/typikon, pl. τυπικά/typika, lit. "following the order"; Slavonic: ѹставъ/ustav) is a book of directives and rubrics that establishes in the Orthodox Christian Church the order of divine services for each day of the year. It assumes the existence of liturgical books that contain the fixed and variable parts of these services.. (Wikipedia https://en.wikipedia.org/wiki/Euchologion, OrthodoxWiki https://orthodoxwiki.org/Hieratikon)