 While this type of script is convenient in Semitic languages like Arabic and Hebrew, whose consonant roots are the key of the sentence, Urdu is an Indo-European language, which does not have the same luxury, hence necessitating more memorisation.The number of letters in the Urdu alphabet is somewhat ambiguous and debated.Tāʼ marbūṭah is also sometimes considered the 40th letter of the Urdu alphabet, though it is rarely used except for in certain loan words from Arabic.