Two years ago today, on 9 July 2024, the first commit to Ooloi went in. Time to take stock.

There's no music on screen. Two years in, and still not one printed note. No noteheads. No beams. No slurs. No page of music. All true, all planned, and all completely beside the point.

Why? A notehead drawn in the first year would've been a comfort object, not evidence. So the visible surface stayed sparse on purpose while the real work went on underneath it. The absence of staves was never the interesting fact about this project. It was the cost of getting the interesting facts right, and this anniversary is the point at which they start becoming visible.

This isn't an eccentric way to build notation software. It's how the serious ones are built, and the record is consistent. Sibelius took its two founders about seven years before the first release in 1993. MuseScore was carved out of a sequencer in 2002 and did not reach a stable 1.0 until 2011. Dorico, built by most of the old Sibelius team after they were let go, took close to four years and shipped its first version deliberately slow and incomplete, engine and engraving model first; the field judged the decision sound. Three programs, three decades, open source and commercial alike, and in every case the foundational years came before anything a user would recognise as finished.

The counter-example proves the same point from the other side. Finale shipped fast in 1988, did more than anything before it, and became the industry standard for a generation. It was also, by wide agreement, punishing to use, and when its owners finally discontinued it in 2024 they said plainly that decades of accumulated code had made each new version harder to deliver and worth less. Feature piled on feature until the architecture could no longer move. That's the ceiling a notation program hits when the surface is built before the foundations are right.

Two years isn't a long time to spend getting the foundations of a fifty-year program right, and I've never regarded it as a delay.

Now, the bet on which Ooloi is built is functional programming. Music notation is a genuinely hard computer science problem wearing a friendly costume, and Clojure's properties looked to me like the right machinery for the parts of it that commercial programs have learned to manage rather than solve. Ooloi is my first Clojure project, though not my first Lisp by a long way, so the syntax was familiar ground; an old hand picks up a new dialect quickly.

The deeper reorientation was immutability. Fully embracing immutable data structures, rather than merely tolerating them, changed how I thought about the whole domain, and almost everything architecturally distinctive about Ooloi fell out of that one shift. Undo, collaboration across machines, full use of multi-core parallelism, pervasive structural sharing: none of these is a feature bolted onto mutable objects. Each is a consequence of representing musical facts as immutable values. Learning to think that way was the real work of the first stretch.

The harder part was psychological. A screenshot of notation would've been reassuring, and I could've produced something theatrical early on if theatre had been the goal. I grew up around theatre. I know a backdrop when I see one. I also know there's never a wall behind it.

So the project spent a long time with most of its real work below the surface. The documentation was public, the ADRs were public, the blog was public, but the evidence still required reading. And the focus on the yet invisible might have given the impression that progress had been slow. So I drew up a list of what's been completed over the past two years.

I expected it to be useful. I did not expect it to be quite so long.

That surprised me, which is perhaps the point of doing the accounting at all. Daily work doesn't feel like accumulation. It feels like the next ticket, the next invariant, the next small refusal to leave a problem in a shape that'll charge interest later. Only when the pieces sit next to each other does the scale become visible:
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• Core musical model: Pieces, musicians, instruments, staves, measures, voices, rhythmic items, attachments, traits, hierarchy, and the basic vocabulary for representing musical facts.
• VPD addressing: Vector path descriptors, giving operations precise structural addresses inside a piece.
• STM coordination: Transactional backend state, with Clojure STM used as the coordination model for musical mutation.
• Timewalking: Temporal traversal of nested score structure, including the transducer-based breakthrough that made the score streamable in musical order.
• Pitch representation: Exact spelling, rational arithmetic, transposition machinery, and round-trip integrity.
• Time signatures: Ordinary, additive, mixed-unit, fractional, irrational, historical, and descriptor-preserving signatures.
• Key signatures: Standard modes, keyless notation, custom signatures, per-octave variants, and microtonal systems.
• Remembered alterations: Deterministic accidental handling built on pitch, time, key context, and traversal.
• Measure distribution: Formal specification of measure distribution as a Knuth-Plass-style optimisation problem.
• Persistence and compression: Serialisation, structural sharing, hash-consing, and the 50,000-note compression test.
• gRPC API: Generated method exposure, Protocol Buffers conversion, streaming, bounded queues, events, and the unified value transport.
• Server statistics: HTTP metrics, health endpoints, and the monitoring machinery used to validate server behaviour. Grafana and Prometheus support.
• TLS and transport hardening: Secure transport foundations, connection handling, shutdown correctness, friendlier errors, and combined-app collaboration TLS.
• Reference-passing transport: Near-zero-overhead in-process calls by removing the Clojure-to-protobuf conversion path inside the desktop app.
• Integrant system architecture: Component lifecycle, dependency wiring, startup, shutdown, and the shared/backend/frontend division.
• Frontend event architecture: Event bus, backend event router, category batching, wildcard subscription, invalidation routing, and JavaFX-thread discipline.
• Backend-authoritative rendering design: Terminal frontend execution, paintlist boundary, cache hierarchy, and backend ownership of musical layout decisions.
• Localisation: PO-file workflow, strict translation-key discipline, canonical UK English, runtime locale switching, build-time checks, and 22 bundled locales: Czech, Danish, German, Greek, UK English, US English, Spanish, Finnish, French, Hungarian, Icelandic, Italian, Japanese, Korean, Norwegian Bokmål, Dutch, Polish, Brazilian Portuguese, European Portuguese, Swedish, Ukrainian, and Simplified Chinese.
• Frontend settings: Persistent application settings, registry-driven defaults, validation, generated Settings window, and reactive updates.
• Window lifecycle: Declarative window opening, persistent geometry, fade behaviour, modal gating, and centralised stage management.
• UI styling: Semantic styles, no hardcoded colour seepage, custom cljfx components, and Java interop confined to boundary files.
• Notifications and chrome: Splash screen, platform menus, notification overlay, menu-bar host, About window, settings UI, and orderly shutdown.
• Frontend undo and redo: Local undo history for application settings, integrated into the same menu surface as backend undo.
• Backend undo and redo: Resource-level undo manager, coordinated history, localised descriptions, frontend routing, clock-offset adjustment, and cross-client undo.
• Instrument Library: Real instrument and staff records, editing, validation, persistence, conflict retry, drag-and-drop, deletion tombstones, ordering, multilingual contents, and a complete populated default library.
• Font management: Bundled SMuFL fonts, associated text fonts, font registry, and glyph-selection architecture.
• Transaction-driven distributed updates: The whole update model. A change is a transaction against authoritative backend state; committing it names what's now stale, and every subscribed client, on the same machine or across the network, refetches the canonical structure and replaces its view. No deltas, no merge logic, no distributed-specific code paths. Collaboration is not a separate engine; it falls out of this for free.
• ​Collaboration architecture: Dual-server model, local and network transports sharing backend state, frontend transport switching, host and guest roles, connection UI, and shared resource editing.
• Two-laptop proof: Guest edit, host observation, host undo of the guest's change, propagation back to the guest; and, at the two-year mark, musicians created and rearranged in a shared piece window on one machine and appearing on another.
• Post-demo hardening: Collaboration menu enablement, backend-switch undo-cache invalidation, standalone backend wiring, collaboration palette behaviour, anchor-first selection, modal menu gating, TLS routing, friendly errors, and headless test mode.
• Platform support: macOS Apple Silicon, Windows x86_64, Linux x86_64, native bundles, Windows application build, and an explicit platform policy.
• Documentation: ADRs, guides, development log, reading path, and Librarian, built as part of the system's survival machinery.
• Test infrastructure: Shared, backend, and frontend tests, now around 24,400 passing cases.
• Piece Window: Structural entity identity and cloning, opaque backend filesystem navigation, a component-owned piece-manager store, a custom Open/Save picker that never sees paths, a complete piece file menu (New, Open, Save, Save As, Close) with typed and translated failure messages, transport-blind file commands that work unchanged in a collaboration, deterministic backend close-on-last-release, and a piece window that's now a live view of authoritative backend state, updating across every subscribed client on any structural change.

During daily work, a subsystem closes and vanishes from attention. That's partly the method: finish something completely enough that it stops sharing the desk. The Instrument Library no longer asks to be designed. Localisation no longer asks to be invented, and the interface already speaks twenty-two locales. Undo no longer waits behind every future feature (with a small knife). Transport no longer converts itself through protobuf in-process for no reason. Window lifecycle no longer belongs to individual windows. Each closed subsystem removes one more thing from the cognitive field.

The list makes visible what the surface hid. Ooloi hasn't spent two years waiting to become a notation program. It's spent two years removing the taxes a notation program would otherwise pay forever.

This is also where the unusual working conditions matter. I've been ... unburdened by people. That sounds harsher than I mean it, though perhaps not by much. Not unburdened by readers, musicians, criticism or conversation, which have all mattered, but by the organisational forms that force software to explain itself before it has finished thinking. No investors, no release calendar, no committee, no inherited user base demanding that a workaround stay sacred because muscle memory has mistaken it for design.

A team would have made some things faster and some things impossible, or at least premature. There's a stage in a project like this where the architecture has to be held whole in one mind, not because one mind is superior to several, but because dividing the thing too early changes the thing. Ooloi needed a period before that could happen.

That period has had its own cost. Solitude removes obstruction, but it also removes alibis. Every accepted decision is mine. Every inconsistency in the documents is mine to catch. Every time Claude Code proposes a convenient shortcut, I have to know whether it's harmless, local, or the kind of thing that looks harmless now and grows teeth later. There's no one else to blame, which is excellent architecture and poor comfort.

The AI has made the solitude more productive, though only because the architecture constrains it. Claude works best as an implementor inside settled boundaries. Give it one subsystem, clear invariants, failing tests, and a narrow target, and it moves with astonishing speed. Ask it to hold the whole system in its head at once, and it becomes what all of us become under those conditions: less intelligent than advertised. Every subsystem sealed below the musical floor is one fewer thing it has to juggle when the visible engraving work begins.

That's another reason the long groundwork was worth doing. The cleared desk isn't a metaphor I use lightly. It's how the next phase becomes possible.

The 3 June proof mattered because it compressed much of this into one modest action. Two laptops. One Ooloi hosting, one connected. A flute name changed on the guest, visible on the host. Undo on the host, reverting the guest's edit. The revert appearing on the guest.

As cinema, it will not trouble Bergman. As architecture, it was the exact kind of evidence I had been waiting for.

That little proof did not show engraving, and it did not pretend to. It showed authority, transport, shared state, invalidation, fetch, undo routing, and cross-machine propagation acting together without ceremony. Nearly two years of decisions appeared as a small correction to the name of a flute. Software milestones are sometimes like that: not fireworks, just a door opening without sticking because someone spent a very long time caring about the hinge.

Now the work is moving towards the page.

The custom picker is already visible and operable. It's not a native file chooser with new paint. It asks the backend what exists, receives opaque tokens, and never sees paths. Local storage and remote storage go through the same contract. The boring dialog is already the front edge of the piece model.

Behind it, the piece window is now a live view of authoritative backend state, and this anniversary comes with a second small proof to show it. The video accompanying this post was recorded on two machines. On one, a wind quintet is assembled in a handful of gestures: flute, oboe, clarinet, horn, and bassoon dragged out of the Instrument Library into the Musicians panel of a shared piece window, each becoming a musician with its staves beneath it, and then dragged across into the Layouts panel to define the full score and the five individual parts. On the other machine, the same piece window answers. No delta is sent between them: a structural change names what is now stale, and the other screen refetches the canonical structure and redraws.

It's the 3 June proof one storey higher. In June a flute changed its name and the plumbing held; here the same architecture carries piece structure rather than a library entry, edited collaboratively, with the invalidate–fetch–replace model the Instrument Library established generalising to the piece itself unchanged. And it's still, deliberately, not engraving. What crosses the wire and appears on the second screen is musical structure, not a rendered stave. There's no notehead in the video. The machinery that'll carry the music is running, and running across two machines, before the music arrives.

Next come piece preferences and window persistence, the rest of the Piece Window arc. After that, MusicXML, because real scores must drive real notation work. Then Skija and the rendering pipeline. Then the noteheads: spacing, stems, flags, dots, accidentals, voices, collisions, beams, ties, slurs, hairpins, lyrics, pedalling, ottavas, tuplets, and the geometry of the page.

The evidence will change again at that point. The collaboration you can already see in the video will still be there, but it'll be moving notation rather than structure. A slur will find space. A beam will sit, straddle, or hang. A note in a chord will change geometry around it. One screen will alter shared musical notation and another will answer with the same page. The program will make the argument in engraving, not only in structure.

I'm looking forward to that more than I can sensibly say.

Two years in, the thing that surprises me isn't that there's still no music on screen. I expected that. The noteheads were never beside the point as a goal, only as evidence; a program isn't proved by what it can draw first. The surprise is how much of the project is already behind the moment when music appears. The empty stave, seen from the surface, suggests absence. The inventory tells a different story: a great deal has already been decided, tested, closed, and made boring.

Boring is underrated. Boring is what a foundation becomes when it's doing its job.
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So, coming out from the darkness that never really was, the next part will be visibly brighter, and with any luck it will involve fewer ... certificate files.

​A few weeks ago I wrote a post explaining computer science terminology to musicians. This is the inverse: an explanation of music notation for programmers who assume the domain is simpler than it is.

That assumption is common. It's also expensive. Most notation software has been written by very competent engineers who underestimated the problem. The result is systems that work impressively until they don't – at which point they fail in ways that seem arbitrary to users but are, in fact, architectural.

This post explains why.

​Here is a concrete example of why music notation is harder than it looks.

Question: Does this F need a sharp sign?

Answer: It depends on:

1. The key signature (established possibly pages earlier)
2. What happened earlier in this measure in this voice
3. What happened earlier in this measure in other voices on the same staff
4. What happened earlier in this measure in other staves (in keyboard music, an F♯ in the left hand may affect an F in the right)
5. Whether there's a tie from the previous measure
6. Whether this is a grace note (different rules apply)
7. Publisher conventions (some always mark cautionary accidentals, some don't)
8. Historical period (18th-century conventions differ from 20th-century)

A naive algorithm checks each note against previous notes in the measure. This is O(n) per note, O(n^2) per measure. Fine for simple music.

Now add multiple voices. The F in the soprano might be affected by an F♯ in the alto, depending on conventions. You need to track alterations across voices. If voices cross staves (as in keyboard music), the interactions multiply.

Now add simultaneity. What happens when two voices sound the same pitch at the same instant but with different accidentals? Yet another edge case difficult to catch when imprisoned in the Jail of Recursive Descent.

Now add grace notes. A grace note at the beginning of a measure might be notated at the barline but sound at the end of the previous measure. Does its accidental affect the next measure? Does the next measure's key signature affect it?

The dependency graph for accidentals is not a simple sequence. It's a directed acyclic graph with edges determined by temporal position, voice membership, staff assignment, and notational category. Correct handling requires topological sorting with domain-specific edge semantics.

Most notation software handles this with heuristics: rules-of-thumb that cover common cases and fail on uncommon ones. The failures aren't bugs in the usual sense. They're consequences of architectural decisions made decades ago when the problem was less well understood.

Ooloi handles this through what I call the 'timewalker' – a transducer that processes musical events in semantic order (not storage order) allowing full temporal context accumulation. The accidental algorithm becomes stateless over its input stream: given the same sequence of musical facts, it produces the same decisions. Deterministically. Every time.

The complexity is still O(n · v) for n events and v voices, but the constant factor drops dramatically because traversal and processing are separated. The transducer handles navigation; the algorithm handles meaning.

​Here is where most notation software fails silently.

A modern computer has multiple cores. Users expect responsiveness: type a note, see it appear immediately. But notation isn't like a word processor where inserting a character affects only nearby layout. Changing one note can alter accidentals throughout a measure, reflow an entire system, or invalidate cached engraving calculations across pages.

The traditional approach is to serialise everything. One thread handles all mutations. The UI blocks or queues. This is why notation software freezes when you paste a large passage, or why collaborative editing remains essentially unsolved in this domain.

The problem deepens when you consider what 'correct' means during an edit. If a user changes an F♮ to an F♯ in measure 4, the accidental state of measure 5 depends on this change. But if the rendering thread is currently drawing measure 5, what does it see? The old state? The new state? Some inconsistent mixture?

Mutable state with locks doesn't solve this; it creates a new category of bugs. Deadlocks. Race conditions. Heisenbugs that appear only under specific timing. A very difficult work environment indeed, and one where diminishing returns becomes a real impeding factor.

The functional approach is different. If musical data is immutable, the question dissolves. The rendering thread has a consistent snapshot – always. The editing thread produces a new snapshot. There's no moment of inconsistency because there's no mutation.

This is what Software Transactional Memory provides in Clojure. Transactions compose. Reads are always consistent. Writes are atomic. The system guarantees that no thread ever sees a half-updated score.

The performance implications are substantial. Ooloi's STM handles heavy contention without the coordination overhead that serialised systems pay constantly. The bottleneck shifts from synchronisation to actual work.

Real-time collaboration becomes architecturally possible. Two users editing the same passage don't corrupt each other's state; they produce alternative futures that the system can merge or present as conflicts. This isn't a feature bolted on afterwards. It's a consequence of representing music correctly from the start.

​Programmers sometimes assume that once you have the musical data, displaying it is straightforward. Calculate positions, draw glyphs, done.

This underestimates the problem by roughly an order of magnitude.

Consider accidental placement in a dense chord. Multiple accidentals must avoid colliding with each other, with noteheads, with stems, with ledger lines, and with accidentals in adjacent chords. The placement rules aren't arbitrary – they encode centuries of engraving practice optimised for readability.

This is a constraint satisfaction problem. In the general case, it's NP-hard. Real systems use heuristics, but the heuristics are subtle. Gould's Behind Bars – the standard reference on notation practice – devotes many pages to accidental stacking alone.

Now multiply by every other engraving decision: beam angles, stem lengths, tie curves, slur routing, dynamic placement, tuplet brackets, ottava lines, system breaks, page breaks. Each interacts with the others. Change a stem length and the beam angle needs adjustment; beam ends need to follow sit-straddle-hang rules and might both move. Change a beam angle and adjacent voices may collide.

LilyPond's engraving quality comes precisely from treating this as a serious optimisation problem. Its page-breaking algorithm runs a variant of the Knuth-Plass line-breaking algorithm (developed for TeX). Its spacing uses spring-based constraint systems. The 'simple' rendering layer contains some of the most sophisticated code in the system.

Interactive notation software faces an additional challenge: these calculations must be fast enough for real-time editing. You can't spend ten seconds optimising layout every time the user adds a note. The tension between quality and responsiveness has driven much of the architectural evolution in this field.

​A programmer encountering music notation for the first time will find countless apparent inconsistencies. Surely these could be rationalised?

No. Or rather: not without destroying information.

A fermata on a note means 'sustain this note'. A fermata on a barline means 'pause here'. A fermata on a rest means something slightly different again. These distinctions emerged from practice. Composers use them. Performers understand them. A system that normalises them into a single 'fermata event' loses musical meaning.

Grace notes in Bach are performed differently than grace notes in Chopin. The notation looks similar. The performance practice differs. A system that treats all grace notes identically will produce correct output that performers find misleading.

Clefs change meaning by context. A C-clef on the third line is an alto clef; on the fourth line, a tenor clef. Same symbol, different staff position, different meaning. This isn't legacy cruft – orchestral scores routinely use multiple C-clef positions because different instruments read different clefs.

Mensural notation (pre-1600) has entirely different rules. The same notehead shapes mean different things. Accidentals follow different conventions. Barlines serve different purposes. A truly comprehensive notation system must handle this or explicitly disclaim it.

The temptation to clean this up, to impose regularity, to treat historical conventions as technical debt – this temptation must be resisted. These conventions encode musical knowledge. Destroying them in the name of consistency destroys the knowledge.

​All of this serves a purpose that has nothing to do with computers.

Notation exists to communicate with humans. Specifically: performers who bring interpretation, physical constraints, and centuries of inherited practice to their reading.

This isn't sentimental. It has engineering consequences.

A page turn in the wrong place forces a pianist to stop playing or memorise a passage. This is a functional failure, not an aesthetic preference. The page-breaking algorithm must allow this to be modelled.

Awkward beam groupings obscure metric structure. The performer reads beats through beam patterns. Wrong beaming means wrong emphasis. The beaming algorithm must model this based on the currnent time signature.

Unclear voice leading forces performers to decode the texture before they can interpret it. The system must make voices visually distinct in ways that match musical distinctness.

Engraving choices that are mathematically equivalent may not be performatively equivalent. Two layouts might use the same space and avoid all collisions, but one reads naturally and the other requires active deciphering. The difference matters.

This is why notation is not a solved problem. The specification is 'communicate musical meaning to human performers'. That's not a format spec. It's a design constraint that touches every decision in the system.

Music notation looks like a data format problem. It is actually a meaning representation problem with a millennium of accumulated context.

The systems that fail – and most fail in some way – do so because they treat notation as something to be processed rather than something to be understood. They model the symbols without modelling what the symbols mean.

The systems that succeed take the domain seriously. They represent time exactly. They handle multiple hierarchies without forcing false containment. They process context correctly even when context is non-local. They treat engraving as a real problem, not a rendering detail. They preserve historical conventions because those conventions carry meaning.

This is why Ooloi's architecture looks the way it does. Rational arithmetic isn't ideology; it's the only way to represent tuplets exactly. Immutability isn't fashion; it's the only way to guarantee that accidental decisions are deterministic. Transducers aren't showing off; they're the cleanest and most efficient way to process a semantic stream with accumulated context. STM isn't over-engineering; it's the only way to achieve both correctness and responsiveness without sacrificing either.

The domain dictates the tools. Not the reverse.

​I'm re-reading Gardner Read's Music Notation from 1974. I bought my copy in 1977, which makes me 16 at the time – old enough to take it seriously, young enough to believe comprehensive understanding was achievable through diligent study. Later, this book would influence Igor Engraver's formatting decisions, though not always in ways I'd care to defend today.

What strikes me now is what Read doesn't cover. There's nothing about ledger line thicknesses, actual distances in spaces between noteheads and accidentals, sit-straddle-hang rules, slur curvatures, or tie formatting. None of the engraver-level detail that Elaine Gould's Behind Bars (2011) and Ted Ross's The Art of Music Engraving & Processing (1970, but I didn't discover it until much later) document so comprehensively. Read gives you musical orthography – what symbols mean and when to use them – but not typographical execution.

​When Magnus Johansson published examples of Igor's output on NOTATIO recently, I experienced that particular species of discomfort that comes from seeing your 25-year-old work through 2025 eyes. The ledger line thicknesses were wrong. The beam slants were inconsistent. We clearly knew nothing about sit-straddle-hang.

So what made Igor well-received? Not typographical perfection, that's certain.

First, integrated parts. Only Composer's Mosaic had them at the time, and Igor had them long before Finale or Sibelius. This alone solved a workflow problem that cost professional copyists days of manual labour.

Second, the user experience didn't fight the music. After spending years with Finale on The Maids – full score, parts, piano reduction – I ended up hating Finale. I've called it 'as user-friendly as a cactus' more than once. Creating something that didn't actively work against the creative process was evidently a sufficient innovation.

Third, note entry was fast and powerful. The modal Flow Mode interface that would later vanish completely from notation software for 23 years gave professional users substantial note entry and editing speed improvements. When you're saving many hours per score, you'll forgive a few ledger lines being slightly too thin – and there was a setting for that anyway.

Fourth, we had stellar MIDI playback and a semantic model that made things consistent rather than a collection of rules-of-thumb. That alone provided predictability. And everything could be adjusted – the absence of automatic sit-straddle-hang rules just meant more manual interventions.

The landscape in 1996 made these trade-offs reasonable. The streamlined experience outweighed what we today immediately see was missing.

​2025 is not 1996.

The leading programs have improved considerably since 1996. They're genuinely competent at beam placement and formatting – not flawless, but competent enough that egregious errors are rare.

A new program entering this landscape must get the foundations correct from day one. Beam placement, slurs, ties, accidental positioning – these must be flawless, not 'good enough to ship'. The field has progressed, and users' baseline expectations have risen accordingly.

This is as it should be. But there's something deeper that hasn't been solved.

Here's what I've stated repeatedly: Ooloi is not about 'disruption' or market share. The entire motivation is to escape what commercialism leads to and create something modern, scalable, and architecturally correct from the ground up. Why? Because music notation is an extremely messy and difficult field of computation, and it requires correctness to address its long-standing problems of scalability and accuracy.

This starts with internal representation.

The old programs – and many modern ones still in broad use – were all based on a paradigm inherited from MIDI. MIDI was the standard for pitch representation at the time, and all notation software needed MIDI output for playback anyway. This meant pitches were MIDI numbers (0-127) with attachments indicating whether they were sharp or flat. Figuring out musical context – for instance, to determine what accidentals to draw – had to be derived from something with no connection to musical structure whatsoever. It had to be inferred from context each time.
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That's at the root of the problems programs still have with accidentals. The internal representation is designed around the presentation – the visual aspect – not around the meaning, the semantics, of the music.

And of course, MIDI has no concept of microtonality, which is why notation programs struggle with microtonal entry, presentation, and playback.

Furthermore, for duration, these early programs based their rhythmic representation on a raster of 480 subdivisions – ticks – of a quarter note (TPQN: Ticks Per Quarter Note). A quarter note is 480 ticks long in some arbitrary tempo, an eighth is 240, and so forth. This is the equivalent of pixels in a JPEG, which means there's a limit to what the raster can represent.

The number 480 isn't evenly divisible by very many factors. This leads to all the problems we're still seeing in music notation programs. Various kinds of duct tape – rules of thumb, arbitrary rounding, tolerance spans – have to be used. When tuplets are nested, the approximation errors compound. We're still seeing the effects of this unfortunate MIDI heritage in 2025.

A MIDI-derived representation centred on presentation – the visual aspect – will always have difficulty interpreting what the music means. That interpretive layer is essential for presenting it correctly and consistently.

For that, you need a semantic model, which turns this on its head. The representation is 'musically correct' and detached from its presentation. Once this is in place, you can make informed decisions instead of relying on rounding and rules-of-thumb. It also makes things like playback trivial, which in MIDI-based systems is paradoxically complex.
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​Igor Engraver was, I believe, one of the first programs – possibly the very first – to use a fully semantic internal model. It was also the first to model the real world by using Musicians playing Instruments, which allowed new and powerful abstractions.

It's interesting that Dorico also has this arrangement, though they call their Musicians 'Players' – but it's the same thing. I have no idea whether Daniel Spreadbury was inspired by Igor here, but it's not unlikely. On the other hand, introducing Musicians/Players into the representational hierarchy is a logical choice once you commit to semantic modelling.

I'm not certain Dorico has a fully semantic model, though it's closer than any other program I know of. LilyPond doesn't, despite its sophisticated batch nature. One telling diagnostic: look at how they handle remembered accidentals for grace notes, and how they treat them rhythmically. Another: how durations are represented. If they're floating-point numbers, they're approximations. For true accuracy in all situations, you need rational numbers – infinite precision, always correct. Anything else eventually leads to problems.

If a program has problems with edge cases or behaves inconsistently when dragging things cross-staff, check how it represents pitch and duration. If floating-point is involved, or rasters of ticks (480 or otherwise), the representation isn't semantic. The program might still handle 95% of hairy accidental placements competently. But when it starts having problems with tied notes across key changes or grace notes at measure starts, you know rules-of-thumb are involved – which means results can never be fully deterministic.

Ooloi is fully semantic with the explicit intention of making results fully deterministic.

This might not matter if you're satisfied with what capable commercial programs achieve today. That's legitimate – they handle about 95% of cases well. But if you depend on the remaining 5%, or if you spend your days as an engraver adjusting those 5% repeatedly, then you understand what I mean by deterministic results saving considerable time.

Now, on to Gould and Ross – books that weren't available when Igor was created. We'd inevitably have implemented their specifications had we had time. But as you know, I was ousted from my own company by venture capital pop zombies before we could. They thought guitar tablature was more important than correct engraver-level beaming.

This time, there will be no guitar tablature at the expense of correct beaming and orthography. All things in their proper order. Lead sheets are kid's stuff, comparatively speaking, and will be added later as plugins.

​Bärenreiter, Durand, Peters, Schott, Universal Edition. Publishers whose engravers spent ten years learning how to disappear behind their craft.

The copper-plate aesthetic: bold, confident, generous. Staff lines weighty enough to guide the eye, noteheads round enough to feel sung, stems drawn with conviction.

Modern digital engraving forgot this. It grew thin, bloodless — optimised for screens instead of for musicians.

The lineage is clear, and the standard unchanging: those 1920s scores, those shortened ledger lines, that unspoken discipline that still knows how to sing.

We all worship at that shrine.