<P> After all this, there were only 17 letters that were different in shape . One letter - shape represented 5 phonemes (bt 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 Image: Hebreu hist arabe. png . </P> <P> 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 . </P> <P> The Arabic alphabet is first attested in its classical form in the 7th century . See PERF 558 for the first surviving Islamic Arabic writing . </P> <P> In the 7th century, probably in the early years of Islam while writing down the Qur'an, scribes realized that working out which of the ambiguous letters a particular letter was from context was laborious and not always possible, so a proper remedy was required . Writings in the Nabataean and Syriac alphabets already had sporadic examples of dots being used to distinguish letters which had become identical, for example as in the table on the right . By analogy with this, a system of dots was added to the Arabic alphabet to make enough different letters for Classical Arabic's 28 phonemes . Sometimes the resulting new letters were put in alphabetical order after their un-dotted originals, and sometimes at the end . </P>

When was arabic written for the first time