Braille contractions

Measured against liblouis 3.39.0 (en-ueb-g2), the reference implementation braille displays and embossers run, over the 5,000 most common English words: 99.98% of words identical — 4,999 of 5,000, and on the one word left the rulebook sides with this engine rather than the reference. That comparison is published with its method and its corpus, so the figure can be re-run rather than taken on trust. The method, and the one disagreement, are published in full.

• All 75 shortforms (ab for about, bec for because, brl for braille)
• All 33 initial-letter contractions as standalone words (one, day, time, their, question)
• All 12 final-letter contractions (-ment, -tion, -ness, -ful, -ity, -ance and the rest)
• Shortest-form selection — where several spellings are valid, the one with fewest cells is chosen
• All 23 alphabetic wordsigns (but, can, do, every, from, ...)
• All 19 strong groupsigns (and, for, of, the, with, ch, sh, th, ...)
• Strong wordsigns standing alone (child, shall, this, which, out, still)
• The lower groupsigns ea, bb, cc, ff and gg, with the rule that keeps them between letters (read, rubber, bigger — but not sea or eat)
• The con- and dis- prefixes, including the spellings that are not the prefix (contact but not cone, display but not disc)
• The lower wordsigns be, enough, his, in, was and were standing alone
• Initial-letter contractions inside longer words as well as alone (b-one, ph-one, net-work, part-y), by the rule the rulebook gives each of them (10.7.1 to 10.7.9). They are used wherever their letters occur, with the three tests that spelling settles applied as written — the sign for one not after an o (Boone), ever only where the letters are not preceded by e or i (believer), under not after a or o (flounder) — and, where a rule turns on how the word is said, the rulebook's own examples are the rule: the words it writes without the contraction are held in the engine, an inflection of each allowed
• Bridging (10.11): no groupsign reaches across the join between the parts of a compound word — cart-horse, grass-hopper, knight-hood — or across a prefix where the letters are ea (re-action, re-assure). Which words are compounds is a fact about English and not about braille, so the engine holds the words the rulebook names rather than a rule for finding them
• The UEB Shortforms List in full: all 1,065 entries — the 75 shortforms, the 537 longer words the 2024 Appendix 1 lists, and each of those with s added — come out identical to the reference
• The be- prefix, which applies only where be is a syllable of its own — begin and become take it, best and bench do not. That distinction is about pronunciation, so it follows the reference implementation's own patterns: 98.4% agreement across all 3,676 English words beginning be
• Words spelt like a shortform, which are written so they cannot be read as one — agst drops its contraction, and ab, which has none to drop, takes a grade 1 word indicator instead
• Shortforms carrying an ending: friends, friendly, friendless, greatest, declared, receiver. An added s is allowed on every shortform but about, almost and him, as rule 10.9.5 says; the other endings allowed are the ones measured safe, because shoulder is not should plus an er
• The UEB Shortforms List as the 2024 Rules of Unified English Braille define it (Appendix 1): the listed longer words that keep a shortform inside them — boyfriend, hereafter, goodbye, unsaid — and, by rule 10.9.3, every word with braille or great in it, children where no vowel or y follows, and blind, first, friend, good, letter, little or quick where they begin a word with no vowel or y after them (Braillette, Letterkenny, but Goodacre spelled out); each of them with s added
• A letter standing alone takes the grade 1 indicator, so it cannot be read as its wordsign (plan b, x-ray, B's)
• Letters that would otherwise read as a longer word holding a shortform take a grade 1 indicator (rules 10.9.8 and 10.9.9): Blvd, LLC and ozbrl are marked, llama is not, because little is never used before a vowel
• The strong groupsigns ed, er, ow, ar and gh as whole words standing alone (ed., er–, -ar), which rule 10.4.1 allows wherever the letters occur; ch, sh, th, wh, ou and st are spelled out alone, because each would read as a word (10.4.2). And ing after an apostrophe or bracket inside a word (Ch'ing, brown(ing)), where it is not the beginning of a word (10.4.3)
• The rules of preference that spelling decides: the sign for ence in encea, enced and encer (experienced, silencer — 10.10.6), and the sign for one in words ending oney and in honest and monetary (money, dishonesty — 10.7.6), never straight after an o (Boone)
• Capitals as Section 8 of the Rules of Unified English Braille sets them out: the capitals word indicator for a run of capitals (DipTP, McDONALD'S), the capitals terminator before lowercase letters in the same word (ABCs, WALKing), a capitals passage for three or more words in capitals (CAUTION: WET PAINT!), and no contraction reaching across a capital sign (verY, CliffSide, DeafBlind)

Not covered:

• Compound words the rulebook does not name. Bridging is applied from a list, so a compound it has never seen — one coined last week, or a surname — is contracted straight through, which is what this engine did everywhere until 18 September 2026
• Context rules that depend on syllable boundaries or pronunciation
• Typeform indicators for bold, italic and underline
• Capitals choices the rulebook leaves to meaning (8.8.2): TVOntario is written in the default capitals word mode, not with Ontario kept whole, and OKd with single capitals

Good enough to read, learn from, and check your work against. Not a substitute for a certified transcription — if the output is going to be embossed for someone to rely on, have a qualified transcriber check it.