CKey Format v0.15.0 — Profile 2 Text Capacity

Status: experimental high-capacity profile. This revision emits format=15 (0F), profile=2. It supersedes Format 0.9.0 for new Profile 2 symbols; decoders retain Format 0.9.0 readability.

Frame and correction

The frame before RS encoding is C7 4B 0F 02 LLhi LLlo payload CRC32C, then deterministic zero padding through byte 209. Profile 2 carries 1–200 UTF-8 or binary bytes in systematic RS(255,210) over GF(256), primitive polynomial 0x11D, primitive element 2, roots alpha^0...alpha^44. The 45 parity bytes give the algebraic bound 2e + s <= 45, including 22 unknown-byte errors.

Canonical finder geometry

The normalized field remains 29 by 29 units with centre (14.5,14.5). The outer boundary is a continuous 0.65-unit rounded square from (0.5,0.5) to (28.5,28.5), radius 3.5. Each corner has exactly one broad, round-capped arc inside the border. In the top-left local corner its centre is (4,4), radius 2.30, stroke width 0.80, and its exterior-quadrant path runs from (1.70,4.0) to (4.0,1.70). Its concave/open mouth faces down-right into the polar matrix. The other corners are reflected copies. Only the top-left arc is split at 225 degrees, with a cap-compensated 0.95-unit visible gap. It is the orientation signature. The 6 by 6 physical-unit corner envelopes remain reserved.

Density and placement

The Cartesian matrix has a 58 by 58 density grid at 0.5-unit pitch and 0.34-unit rounded-square modules. The central polar aperture (radius 10.5), finders, and Grid Key are reserved.

There are 144 equal angular slots, eight dot/arc rings at radii 3.40 + 0.43*r, and a narrow ray dial. Ring-bit runs of length one are dots; runs of length at least two are one round-capped connected arc. The visible length of a four-slot arc equals four adjacent dot slots exactly, while the arc remains a distinct connected module. Rays use 0.52-unit short and 1.20-unit long states. The Grid/Ray/Ring Keys retain their calibration roles.

The native core has framing, RS correction, SVG rendering, and codeword tests. It is not camera-validated; do not advertise Profile 2 as camera-scannable.