These petitionary versicles and responses precede the collects in the Daily Offices (see, e.g., BCP pp. 97-98, 121-122). The suffrages in the BCP are based on those in the Sarum offices, although Suffrages B for Evening Prayer are from a Byzantine evening litany. They are responsive prayers of petition which are usually concluded with a collect.
Glossary definitions provided courtesy of Church Publishing Incorporated, New York, NY,(All Rights reserved) from "An Episcopal Dictionary of the Church, A User Friendly Reference for Episcopalians," Don S. Armentrout and Robert Boak Slocum, editors.