A font is more than shapes on a grid. The best typefaces are intelligent — they know how letters should behave beside each other, adapt to context, and make reading feel effortless. When the Yapiri glyphs were complete, the work of turning them into a proper professional font had only just begun.

That next phase was OpenType.

What OpenType Actually Is

OpenType is a font format — the standard used by virtually every font you encounter today, from system fonts to premium typefaces. What makes it powerful is a layer of embedded logic called OpenType features: a set of rules written inside the font file that tell applications how characters should behave in context.

Without OpenType features, a font is essentially a passive lookup table: codepoint goes in, glyph comes out, always the same. With them, the font becomes active. It can adjust spacing between specific letter pairs, substitute a glyph with a better-fitting alternate depending on what surrounds it, handle the correct rendering of numerals, and much more — all invisibly, without the user doing anything at all.

For a newly designed script like Yapiri, this layer is not an optional refinement. It is the difference between a font that technically works and one that feels natural to read.

The Challenge Specific to Yapiri

Yapiri's 45-character set poses a specific typographic challenge that most Latin fonts never face: a large number of structurally similar characters that must remain visually distinct at every size.

The plain and aspirated stop pairs — p/ph, t/th, k/kh — are related by design, their shapes carrying a family resemblance. In body text, that resemblance is a feature; it groups sounds logically. But it also means that spacing, weight, and contextual rendering have to work harder than usual to keep the pairs readable as distinct characters. A reader who momentarily reads /p/ as /ph/ has misread a different word entirely.

The vowels face a similar challenge from the other direction: they must be strong enough to stand alone as independent characters — not attached to a consonant as in an abugida — while still feeling at home beside any consonant in the set. A badly spaced vowel, or one that sits at the wrong optical height, disrupts the flow of an entire line.

"The best OpenType features are the ones no one notices — because everything simply feels right."

— Font development note, v1.0 testing

The Features Added

Four categories of OpenType features were implemented in Yapiri.ttf, each addressing a specific aspect of how the script reads on screen and in print.

kern
Kerning
Fine-tuned spacing adjustments for every significant character pair. Vowels following open-bowl consonants, stops adjacent to approximants, the hyphen beside any character — all kerned individually so spacing feels optically even rather than mechanically uniform.
calt
Contextual alternates
Certain glyphs have subtly adjusted forms depending on their neighbours. Where two characters with similar strokes sit adjacent, a contextual alternate can shift weight slightly to prevent visual merging at small sizes.
lnum / onum
Numeral alignment
Yapiri's ten numerals (U+F1CC0–U+F1CC9) are designed to sit on the same baseline as the letters, ensuring that mixed text-and-number lines — such as dates, measurements, or numbered lists — read as a single coherent line rather than an awkward collision of heights.
mark / mkmk
Mark positioning
Precise anchor-based GPOS placement ensures the high tone mark (U+F1CD1) attaches correctly above any base character. Mark-to-base anchors define the exact attachment point for each glyph, so the diacritic sits at the right optical position rather than defaulting to a uniform offset.

Kerning: The Invisible Labour

Kerning is the most time-consuming OpenType work in any font, and Yapiri was no exception. With 45 characters, the number of possible adjacent pairs is substantial. Not all of them need adjustment — many pairs naturally fit well — but the ones that do need it require the kind of painstaking fine-tuning that can only be assessed by printing or rendering full paragraphs and reading them slowly.

The pairs that demanded the most attention were those involving Yapiri's approximants — /r/, /l/, /y/, /w/ — which have open, flowing forms that can create either too much or too little visual space when they sit beside closed, compact forms. The /r/ glyph in particular required over a dozen individual kern pairs to read cleanly in running text.

Technical Kerning in the Yapiri font is implemented as class kerning where appropriate — grouping characters with similar shapes into kern classes so that a single adjustment applies intelligently across a family of related pairs, rather than requiring every pair to be specified individually.

The Schwa and the High Tone Mark

Two characters in Yapiri have no direct equivalent in Latin typography and therefore received special attention in the OpenType layer.

The schwa (U+F1CA5) is Kokborok's central vowel — a sound so fundamental to the language that it appears in some of the most common words. Its glyph needed to kern cleanly with the widest possible range of preceding and following consonants, including some very different in shape. It also needed its own optical baseline adjustment to sit at the same visual midpoint as the other vowels despite having a different structural form.

The high tone mark (U+F1CD1) is Yapiri's only combining diacritic — a mark that attaches above the preceding character to indicate high tone on that syllable. The OpenType challenge was implementing GPOS mark-to-base anchors that position it correctly over every vowel in the inventory. Each vowel has a different optical centre, so each required its own anchor coordinate. Too high and the mark floats; too low and it merges with the letter form. Getting this right for all six vowels across multiple rendering environments was one of the most technically demanding tasks in the entire font.

Testing the Features

OpenType features cannot be tested by looking at individual glyphs. They can only be assessed in running text — real Kokborok sentences, real poetry, real proper names with their mix of consonant clusters and vowel runs. The test corpus included common words, place names, proverbs, and the deliberately awkward edge cases: words where two similar glyphs sit adjacent, words where the hyphen falls between a vowel and a stop, numerals embedded in prose.

Each testing pass produced a short list of pairs or positions that still felt wrong. Each list drove another round of adjustments. The font went through this cycle many times before the text below — a single line of running Kokborok — read cleanly at every size from 10px screen text to 48px display.

󱲩󱲤󱲩󱲪󱲤󱲷󱲤󱲩 kokborok — the OpenType test that had to pass at every size Eight characters. Seven kerning pairs. One language rendered with care.

What OpenType Cannot Do (Yet)

It is worth being honest about the current state. Version 2.0 of Yapiri.ttf implements the core feature set: kerning, contextual alternates, numeral alignment, and mark positioning. Features that would require a larger glyph set — such as true stylistic alternate forms for characters that might suit different typographic moods — are planned but not yet in the font. They require the kind of community feedback that can only come from the script being used widely in real writing.

This is not a limitation to apologise for. It is how fonts grow: used, tested, refined, and expanded as the community that writes in them develops a sense of what they need. Yapiri v2.0 is complete enough to write anything in Kokborok beautifully. Future versions will be shaped by the writers who use it.

The Heart of the Matter

Adding OpenType features was an act of care — care for the readers who will encounter Yapiri text, care for the language that text carries, and care for the people whose first experience of reading Kokborok in its own script should feel natural, not laboured.

The font is available to download on the Download page and loads automatically across this entire site. The full technical specification, including the character set and glyph metrics, is in the Script Specification. And if you want to see the font in use, the fastest place to start is the web keyboard.

Yapiri is not just a script for today. It is one built with ambition — a writing system designed to last, to grow, and to carry the voice of the Tiprasa people wherever they write.