The "climacus" is a rapid descending scale figure, written as a single note or a ligature followed by a series of two or more descending lozenges. Anonymous IV called these "currentes" (Latin "running"), probably in reference to the similar figures found in pre-modal Aquitanian and Parisian polyphony. Franco of Cologne called them "coniunctura" (Latin for "joined "). When consisting of just three notes ("coniunctura ternaria") it is rhythmically identical with the ordinary three-note ligature, but when containing more notes this figure may be rhythmically ambiguous and therefore difficult to interpret . The difficulty was compounded in the later half of the 13th century, when the lozenge shape came also to be used for the semibreve. A general rule is that the last note is a longa, the second-last note is a breve, and all the preceding notes taken together occupy the space of a longa. However, the exact internal rhythm of these first notes of the group requires some interpretation according to context .