Tibetan Ra ར

Ra is the twenty-fifth of the thirty consonants and opens the seventh line. It writes an alveolar trill or tap, and it carries more structural work than any other letter in the script.

Ra is one of the three superscripts, one of the four subscripts, and one of the ten suffixes. It can therefore appear above a root letter, below one, after one, or as the root itself, and a reader has to determine which before the syllable can be read. No other letter occupies four positions.

Written above a root letter it takes a shortened form, and in modern Lhasa speech it is silent, its former presence carried by the tone of the syllable beneath it. Written below, it alters the consonant above it rather than sounding. Written as a suffix, it closes the syllable and affects the vowel in front of it.

Because the superscript form is shortened, digital text needs a way to prevent the ordinary shape from combining when a plain ra is wanted next to something it would otherwise stack with. Unicode provides a separate fixed-form character for exactly that case, which is a small example of a very old scribal distinction surviving into an encoding standard.

What ra is not is a prefix. The five prefixes are ga, da, ba, ma and the small a, and ra is absent from that list, so of the positions available in a Tibetan syllable it fills every one except the first.

Above the root letter of a Tibetan syllable there may be a superscript, the mgo can or head letter, and three letters may take that position: ra, la and sa. No others.

All three are silent in modern Lhasa speech. What they do instead is set the tone: a syllable with a superscript is spoken high, even where the root letter would otherwise be low, so the head letter has become a pitch mark on a syllable rather than a consonant in it. In the classical language it is understood to have been pronounced, as part of an initial cluster, and clusters of this kind survive in Amdo speech today.

Two of the three change shape in the position. Superscript ra is written in a shortened form, and superscript la and sa are adapted to sit above the letter they govern. The stack is compact by design, because it has to be read as one unit and fit between two tsheg dots.

Which roots take which superscript is a property of the word and is learnt with it, not derived from a rule. That is the same situation as with the prefixes, and the two together are the reason a Tibetan word cannot be spelled from its pronunciation even by a native speaker who reads fluently. Spelling has to be known, and Tibetan schooling accordingly gives it a great deal of attention.