Katnae is written using a syllabary, similar in complexity and information density, if not appearance, to Hiragana or Katakana. The technical details are elaborated below.
The Katnae writing system is not meant to be written by hand. If handwriting with a pen on paper is something the Katnae — or their ancestors — ever did, it has long ago faded into the murky history of their ultimate origin. The drawing or carving of written symbols onto a surface by hand would seem to modern Katnae to be a form of artwork or calligraphy, not something done solely to record spoken language. Nowadays, all actual writing is done on a computer and has been for as long as anyone has been alive. If a message should need to be transferred to a physical object, typed words would be printed or etched by machine.
As such, the actual shapes of Katnae syllable glyphs can sometimes look quite awkward, as the act of shaping them no longer exerts pressure on their development. Readers are also accustomed solely to what we would think of as monospace fonts, and the reading of handwritten text would likely be difficult for the average literate speaker. Do not, however, assume that this indicates a lack of diversity in Katnae fonts — there are probably more different styles than you might assume at first.
At the moment, however, only one style exists.
Each Katnae orthographic syllable corresponds to exactly one mora of spoken Katnae. As such, calling them syllables might be a slight misnomer, but that term and the term syllabary are sufficiently well established that deviating from the convention would introduce more confusion than it would prevent.
Katnae is typically written left to right, top to bottom, just like the Latin alphabet. While at some level this may just be carryover from Latin and other scripts, it is also not a particularly odd convention cross-linguistically. That said, if anything is likely to be tweaked in this script in the future, the direction of writing would be a very easy choice. Vertical columns, going top to bottom and then either left to right or right to left, would also work just as well.
A full syllable chart is also available, although the tools for actually writing this script — such as fonts — are currently in their infancy. All glyphs have been created by hand-coding SVG images.
Katnae long vowels are traditionally analyzed as sequences of two identical vowels, and the writing system reflects this: a long vowel is written using the zero-initial syllable representing the same vowel as the previous syllable. There is no character equivalent to the Japanese chōonpu/長音符 or diacritical mark that would indicate a lengthened vowel (or for that matter, a long consonant — "long" consonants are also treated as sequences of consonants, which are detailed below).
Similarly, a diphthong is written by placing the zero-initial syllable corresponding to the second part of the diphthong after a syllable whose vowel corresponds to the first part. Katnae does not distinguish between diphthongs and pairs of short vowels in hiatus within a word (either phonetically or orthographically), and word boundaries must be inferred from context.
Syllable-final sonorants are written using the "echo vowel" strategy: write the syllable consisting of the syllable-final consonant followed by the vowel the occurs immediately before it. Any ambiguity between a syllable-final sonorant and a word where a vowel is genuinely repeated after a sonorant is simply tolerated — it doesn't happen very often, and there are dialects in which various sound changes have rendered one or the other reading functionally impossible.
For syllable-final stops — which are not distinguished by place of articulation, and surface as a stop homorganic with a following consonant or as a glottal stop before a pause or a vowel — a special character exists, much like the moraic nasal in Japanese. In standard Katnae, this character is used for all syllable-final consonants that are not sonorants.
In the rare case that one needs to distinguish between two different syllable-final non-sonorant consonants, the echo vowel strategy can theoretically be extended to other consonants. This is never needed in the standard language, but it can be useful for faithfully representing one or two distinctions in a handful of dialects — most notably the distinction between /ts/ and /s:/ clusters — or for writing foreign names or unassimilated loanwords.
As mentioned above, in standard Katnae, there is ambiguity in writing between a syllable ending in a sonorant and one ending in a vowel followed by a syllable consisting of a sonorant followed by the same vowel.
For the most part, Katnae speakers simply live with this ambiguity and allow context to distinguish if necessary. It isn't all that common, and cases that might actually confuse someone are likely vanishingly rare. Additionally, some Katnae dialects insert an echo vowel after syllable-final sonorants in many positions, and others delete a repeated vowel in similar environments, rendering the discrepancy in ambiguity caused by the writing system and that already present in the spoken language functionally nonexistent for those speakers.
That said, there may be a diacritic or other mechanism for marking a syllable to unambiguously indicate that it represents a syllable-final consonant. No such mechanism currently exists or is under construction, though.
Currently there are two punctuation marks: a "full stop" and a "word separator".
The former is a straightforward equivalent to the Latin Alphabet's period, although its exact usage rules are still vague — among other things, it may be more normal in Katnae than in English to leave off the full stop at the end of a sentence if the sentence is at the end of a paragraph, stands alone on the screen, or otherwise unambiguously terminates without the reader having to guess from context and content. There is also no separate question mark in Katnae — a full stop is used at the end of a question under the same criteria that it would be used at the end of a statement.
The latter mark — the "word separator" — poses a greater problem. It was originally intended to be used like the space between words in most modern alphabetical languages on Earth, but after beginning to use the script for more than a couple of syllables at a time, it rapidly became clear that this was both unnecessary and a waste of space. As such, the word separator will probably not remain as a word separator much longer: it will either be removed entirely (less likely), or will take on the function of an exclamation point or focus/emphasis marker placed only after emphasized words.
There is no Katnae punctuation mark equivalent to a comma. Spaces the width of a single syllable can occasionally be used before conjunctions joining larger clauses for readability, but the official best practice is to break up long sentences into shorter ones separated by full stops. In Katnae, the equivalent of "starting a sentence with because" is prescribed rather than proscribed.
So far, we're using lines of thickness 40, with rounded ends. Typical circles have radius 80 (which appears to be inner radius) without any fill. There's probably more that can be done to simplify the process of generating the characters, but this is enough for now.
Dots typically have a radius of 30, and are solid.
All of this is done on a 480x480 grid. That may or may not still be the case in the future, but I doubt I will change too much once I've made all of the files.