The joining or touching of two adjacent letters, either by two letters sharing one stroke or when one letter intrudes upon (or bites) the other. Albert Derolez perfers the term "fusion" to biting; other paleographers consider "juncture" more appropriate. Biting letters appeared in western manuscripts during the 12th century, with the introduction of the uncial form of the letter "d" and other modifications of Carolingian script such as the use of the round "r".