[1] The alphabet, which contains 20 letters, was introduced in the grammar book developed by Lope K. Santos for the newly designated national language based on Tagalog.
Dr. José Rizal was one of several proponents (including Trinidad Pardo de Tavera) of reforming the orthographies of the various Philippine languages in the late 19th-century.
Like other proponents, he suggested to "indigenize" the alphabet of the Philippine languages by replacing the letters C and Q with K.[4] Initially, these reforms were not broadly adopted when they were proposed but gradually became popular into the early 20th century.
Following the establishment of the Philippine Commonwealth in 1935, the government selected Tagalog as basis for a "national language" (i.e. Filipino).
At present, all languages of the Philippines may be written using the modern Filipino alphabet (officially adopted in 1987), which includes all the letters of the Abakada.