came to acquire their modern meanings of raising or lowering notes by a half step. Adrian Le Roy wrote that "b sharpe doeth holde up the tune halfe a note higher, and b flatte, contrarywise doeth lette it fall halfe a note lower".But as early as 1524, theorists also had this understanding of these signs. Moreover, near the beginning of the 17th century, Michael Praetorius employed the words signa chromatica (chromatic signs) to refer to sharps and flats. Hence, musicians of the later Middle Ages and Renaissance did not all share a uniform interpretation of this concept. Practical application The signs b mollis and b durum were not notated with any regularity in vocal sources of the late Middle Ages and Renaissance, and although the principles that singers used to supply the missing information were discussed in theoretical treatises, the explanations are far too cursory to enable modern musicians to reconstruct the old practices with any degree of accuracy. Tablatures, however, because they turn implicit solmization practices into explicit pitches, provide a precise view of how musicians, or at least those in the 16th century, added sharps and flats to vocal sources (the first tablatures were published in the early 16th century). Common practices: Many musicians in earlier times found the linear (melodic) and vertical (harmonic) dissonance caused by clashes between mi and fa aurally offensive (especially when it involved tritones and octaves), and they regularly removed the dissonance. Exceptions to this practice were common, however, particularly at cadences; some musicians even found dissonant octaves acceptable at times. Despite the theoretical prohibition of what Zarlino referred to as occasions when "the parts of a composition do not have a harmonic relation between their voices" ("le parti della cantilena non habbiano tra loro relatione harmonica nelle loro voci"), 16th-century tablatures demonstrate that musicians sometimes removed and at other times retained these clashes. At cadences and other places where two voice parts proceed to an octave or unison, singers normally approached the perfect interval from the closest imperfect interval; when the closest imperfect interval did not occur naturally in the music, singers created it either by adding a sharp to the voice rising by a whole step or by adding a flat to the voice descending by a whole step. These practices were common throughout Europe, but in Germany musicians followed a distinctive set of practices for their own vernacular music, particularly