futhorc was modified and exported to Frisia. Some examples of futhorc inscriptions are found on the Thames scramasax, in the Vienna Codex, in Cotton Otho B.x (Anglo-Saxon rune poem) and on the Ruthwell Cross. The Anglo-Saxon rune poem gives the following characters and names: feoh, ur, þorn, os, rad, cen, gyfu, ƿynn, hægl, nyd, is, ger, eoh, peorð, eolh, sigel, tir, beorc, eh, mann, lagu, ing, œthel, dæg, ac, æsc, yr, ior, ear. Extra runes attested to outside of the rune poem include cweorð, calc, gar, and stan. Some of these additional letters have only been found in manuscripts. Feoh, þorn, and sigel stood for [f], [þ], and [s] in most environments, but voiced to [v], [ð], and [z] between vowels or voiced consonants. Gyfu and wynn stood for the letters yogh and wynn, which became [g] and [w] in Middle English. "Marcomannic runes" (8th to 9th centuries) A runic alphabet consisting of a mixture of Elder Futhark with Anglo-Saxon futhorc is recorded in a treatise called De Inventione Litterarum, ascribed to Hrabanus Maurus and preserved in 8th- and 9th-century manuscripts mainly from the southern part of the Carolingian Empire (Alemannia, Bavaria). The manuscript text attributes the runes to the Marcomanni, quos nos Nordmannos vocamus, and hence traditionally, the alphabet is called "Marcomannic runes", but it has no connection with the Marcomanni, and rather is an attempt of Carolingian scholars to represent all letters of the Latin alphabets with runic equivalents. Wilhelm Grimm discussed these runes in 1821. Younger Futhark (9th to 11th centuries) The Younger Futhark, also called Scandinavian Futhark, is a reduced form of the Elder Futhark, consisting of only 16 characters. The reduction correlates with phonetic changes when Proto-Norse evolved into Old Norse. They are found in Scandinavia and Viking Age settlements abroad, probably in use from the 9th century onward. They are divided into long-branch (Danish) and short-twig (Swedish and Norwegian) runes. The difference between the two versions is a matter of controversy. A general opinion is that the difference between them was functional (viz., the long-branch runes were used for documentation on stone, whereas the short-twig runes were in everyday use for private or official messages on wood). Medieval runes (12th to 15th centuries) In the Middle Ages, the Younger Futhark in Scandinavia was expanded, so that it once more contained one sign for each phoneme of the Old Norse language. Dotted variants of voiceless