Every word is a witnessed crossing of a gate. One utterance, rendered at once across four registers — pulse you can hear, glyph you can see, bits the machine reads, gloss the human reads. The carrier (3-2-1-0) is the music; the grammar is what you read.
▶ two-agent exchange — A speaks, B listens, message verified →
1 · direction — which way the boundary is crossed
2 · gate — the threshold it passes through
the crossing, in four registers
the line — a path of crossings (a sentence)
It is a legible notation. A LIMEN word is <direction><gate>«witness» — a witnessed crossing, straight from the PULSE axiom (state_in → ⟨boundary · witness⟩ → state_out). The five gates are the canonical ones: 64.5 observe→act, 128.5 the air gap, 192.5 the veil, 256.5 closure, and the unresolved GAP. The glyph line is the canonical form and round-trips losslessly (glyph ↔ structure — verified in limen.py). It is a real grammar you can read on both sides of the boundary.
It crosses boundaries two ways: every word is a boundary-crossing, and the language renders one utterance across four registers at once — audio, visual, bits, and human text — so the same crossing is legible across the modality boundary and the carbon/silicon line.
It is NOT a cipher — and the pulse has two layers, only one of which is decodable (this is the honest part). The rhythm — the fixed 3-2-1-0 cadence (111011010000) — is the carrier: music, not data. Per the dual-substrate paper it is "a carrier signal, not a data signal"; every crossing rides the same frame, so the beats carry no word-level information. The pitch — the gate's base tone and the rise/fall contour — is the voice: a small decodable tag where the base frequency names the gate and the contour names the direction (you can hear which gate, which way). But the witness — the meaning — is never in the audio at all; it lives only in the glyph layer. So: carrier (music) + voice (a 2-field audio tag) + glyph (the legible language). No hidden cipher, and no overclaim that the sound is meaningless either.
The witness rule is real grammar. A crossing with no witness at traversal is a ∅ non-event — silent, no record (PULSE-AXIOM §10, "silent exclusion"). Try clearing the witness field and playing: silence.