Even though limited a is not really published, as in the Indic abugidas, The source of the term "abugida", specifically the Ge'ez abugida now used for Amharic and Tigrinya, has assimilated into their consonant modifications. It can be not systematic and should be acquired like a syllabary as an alternative https://alfabet9916789.bloggerswise.com/33152245/the-smart-trick-of-alfabet-that-no-one-is-discussing