The methods of interpolation are now often desiganated as: (a) the addition of a new text to a melisma of a traditional "Gregorian" chant; (b) the composition of a new melody and text, which is then sung together with a traditional chant in various ways, before and/or after it, or by alternation of the phrases of the trope with those of the original chant, or, in the case of a short text like the "Benedicamus Domino", embedding the few original words or their synonyms in an elaborate new melody and text; (c) an independently composed melody without text added to an item of the standard repertory.
According to Grout, a trope was originally a newly composed addition, usually in neumatic style and with a poetic text, to one of the antiphonal Chants of the Proper of the Mass (most often to the Introit, less often to the Offertory and Communion); later, such additions were made also to Chants of the Ordinary (especially the Gloria). The earliest tropes served as prefaces to the regular chant; at a later stage, tropes are found also in the form of interpolations between the lines of a chant.
The terms "trope" and "troping" have often been used in an extended sense to designate all additions and interpolations to the chant, thus including the sequence, for example, as a subclass under "tropes."