History of the Arabic alphabet the same. After all this, there were only 17 letters that were different in shape. One letter-shape represented 5 phonemes ("b t th n" and sometimes "y"), one represented 3 phonemes ("j ħ kh"), and 5 each represented 2 phonemes. Compare the Hebrew alphabet, as in the table at . A similar ambiguity occurs in the German Fraktur font, in which the Roman alphabet uppercase letters I and J look the same but are officially different letters. The Arabic alphabet is first attested in its classical form in the 7th century. See PERF 558 for the first surviving Islamic Arabic
Prosigns for Morse code codes such as Baudot or ASCII. The development of prosigns began in the 1860s for wired telegraphy. They are distinguished from common Morse abbreviations. Since Morse code communication preceded voice communications by several decades, many of the much older Morse prosigns have exact equivalent procedure "words" for use in the more recent radio telephony (voice). Prosigns may be represented in printed material either by a sequence of dots and dashes, or by a sequence of letters, which, if sent without the normal inter-character spacing (concatenated), correspond to the prosign symbol. There are at least three methods used to represent Morse