The liturgy of a particular religious service is the predetermined material that structures that service -- what the priest or other religious officials presiding say and do during the service, where readings from scripture occur and which kinds, where music and prayers occur and which ones, and so on. Syriac Christians of the era would use uniquely-Syriac liturgical material (specific excerpts from religious texts to be read during a service, specific formalized phrases said by the priest, and so on) during church services. In this context a lectionary is a collection of readings from Christian scriptures.