Status: LIVE. Fast definitions for the terms the docs use as load-bearing. Each is grounded in a fuller source; follow the link when the one-liner isn't enough. See the quickstart for these terms in motion and the terminology concordance for the Klir·Bunge·Mobus lineage of each word.
System
A thing-in-relation that holds under a tradition's precondition — not any collection of parts. Whether a described structure is a system is the kernel's verdict, decided per lens, never assumed. See theory-fidelity.md.
Lens
One of the three faithful views the kernel generates from a single model: Klir, Bunge, Mobus. They are not styles or skins — each is a mathematically faithful view entered through its own machine-checked precondition. Author once; read the model as any tradition. See design/lens-palettes.md.
Bond / mere
Bunge's distinction between two kinds of relation. A bond couples distinct components so that one modifies the other's history (Lean criterion FlowInducesAction); a mere relation is any other relation, carrying no such coupling. Bond-vs-mere is author-declared and checked for legality against HasBond, not derived from a run. See theory-fidelity.md (Bunge).
Conservation invariant (declared)
A conserved quantity or bound the model declares on its state space — not a premise the engine assumes. Conservation is one optional declaration among several possible invariants, per the adopted dynamics position. The current engine interprets one such declaration (an additive invariant over ℝⁿ stocks).
WorldModel
The mode-stamped artifact that Export writes: what the author asserts is true as of a given lens, and the object other tools consume. Its mode field records the lens committed to; it does not constrain the data (every model is a valid Core model regardless). See theory-fidelity.md (mode-stamp semantics).
Save vs Export
Save keeps working canvas state — the shape mid-authoring. Export writes a mode-stamped WorldModel: a committed assertion under a lens. A run ledger is neither; it is a result shown in the run panel, not a saved tier. See the README, "What this tool believes".
Run ledger
The per-step accounting a run produces in the run panel: the declared conservation invariant tracked across the run, showing it holds (or where it breaks). A result, not a saved artifact.
SL
The Facets system language: a human-writable, line-oriented textual notation that compiles deterministically (a compiler, never an LLM) into a model. The third concrete syntax over the neutral spec, alongside canvas and JSON. See language/.
Systemhood
The property the kernel decides: whether a model holds as a system under a given lens, versus being a mere aggregate. The SL parser judges no systemhood — legality stays the kernel's verdict. See kernel-architecture.md.
Mode / lens
A mode is the lens an author commits a model to (Core, Structural/Bunge, Operational/Mobus, Full). The modes are parallel lenses sharing only Core's on-ness — a meet-semilattice, not a linear tower — so committing to one lens implies nothing about the others; each is an independent precondition over the same kernel. See theory-fidelity.md.
Neutral spec
The single abstract model that canvas gestures, SL text, and JSON are all concrete syntaxes over. None of the three is the source of truth — the neutral spec is. See language/README.md.
Golden
A committed fixture whose exact output is pinned by a test. The three fixtures/sl/ files are round-trip goldens: each parses, emits, and re-parses identically (crates/bert-canvas/tests/sl_roundtrip.rs). See language/README.md, "Corpus precedence".
Dynamics-kind
The shape of a dynamics record's transition functor — deterministic map, input-driven table, distribution, and so on. A model declares its kind; engines interpret declarations and are separately verified against the semigroup contract. The current engine supports one kind (Id-functor over ℝⁿ stocks). See design/dynamics-principled-position.md.
Precondition
The named, machine-checked hypothesis a lens's entry gate requires: HasBond for Bunge (Structural), Irreflexive for Mobus (Operational). A refusal cites its failed precondition rather than shrugging. Klir is unconditional. See theory-fidelity.md.
Concordance
The Klir·Bunge·Mobus terminology grid: 12 kernel distinctions × 3 traditions, every cell primary-cited. The SSOT for the spec's lexicon attribution and the K≅2 convergence exhibits. See language/terminology-concordance.md.