in france, as in italy, spain and portugal, organs were primarily designed to play alternatim verses rather than accompany congregational singing. the "french classical organ", became remarkably consistent throughout france over the course of the baroque era, more so than any other style of organ building in history, and standardized registrations developed. it was elaborately described by dom bédos de celles in his treatise "l'art du facteur d'orgues" ("the art of organ building").