Page "Alphabet" Paragraph 28

The boundaries between the three types of segmental scripts are not always clear-cut.

For example, Sorani Kurdish is written in the Arabic script, which is normally an abjad.

However, in Kurdish, writing the vowels is mandatory, and full letters are used, so the script is a true alphabet.

Other languages may use a Semitic abjad with mandatory vowel diacritics, effectively making them abugidas.

On the other hand, the Phagspa script of the Mongol Empire was based closely on the Tibetan abugida, but all vowel marks were written after the preceding consonant rather than as diacritic marks.

Although short a was not written, as in the Indic abugidas, one could argue that the linear arrangement made this a true alphabet.

Conversely, the vowel marks of the Tigrinya abugida and the Amharic abugida ( ironically, the original source of the term " abugida ") have been so completely assimilated into their consonants that the modifications are no longer systematic and have to be learned as a syllabary rather than as a segmental script.

Even more extreme, the Pahlavi abjad eventually became logographic.

( See below.