℣ and ℟ are the symbols for “versiculum” (main composition) and “responsum” (refrain), and they are used in psalms, canticles (an example is found on p 97 of the Book of Common Prayer), and responsorial prayers. A versicle is the first half of a preces, said or sung by an officiant or cantor and answered with a said or sung response by the congregation or choir. One of the most familiar examples of this is, “Alleluia, Christ is risen.” answered by “The Lord is risen indeed. Alleluia,” Their are other examples of this format scattered throughout our services. According to our Book of Common Prayer, psalms can by said or chanted in several formats. Direct recitation is the reading of a whole psalm in unison. Antiphonal recitation is the verse-by-verse alternation between groups, between the minister and the congregation, between the choir and the congregation, or between the two sides of the congregation concluding with the Gloria Patri. Responsorial recitation is chosen by some churches. In this format a refrain is first sung by a cantor and repeated by the congregation. The cantor then sings several verses from the psalm interspersed by a reprise of the refrain by the congregation.
~ Dr. Gil Haas