Ha is the twenty-ninth of the thirty consonants and opens the eighth and last line, which has only two members. It writes a voiceless glottal fricative, the h of English hat, and it carries high tone as an initial in modern Lhasa speech.
The line is short because the recitation has run out of material. Thirty letters do not divide into lines of four, and after seven full lines two remain: ha and the great a, which closes the alphabet. Whatever ordering principle governed the first four lines has long since been exhausted by the time a reciter arrives here, and the last line is simply the end.
Ha has one further office in the writing system, outside the thirty. Subjoined beneath a letter it is the device by which Tibetan writes the voiced aspirates of Sanskrit, so that ga with ha beneath it stands for the Sanskrit gha. That is part of the transcription apparatus rather than of Tibetan orthography proper, and it is taught separately.
Ha is also the base of one of the three syllables that stand for enlightened body, speech and mind in Tibetan Buddhism, which is the subject of the article beside this one.
Ha takes superscripts and the ra subscript, and it is not a prefix, a suffix, a superscript or a subscript. In the mechanics of the syllable it is an ordinary root letter, whatever weight the syllables built on it carry elsewhere.