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-# Validate `SG_` signal definitions and report malformed or unsupported syntax
-
-## Description
-
-Following strict validation of `BO_` frame definitions, add equivalent validation for `SG_` signal definitions. Currently, some malformed statements are accepted silently, and unsupported syntax can produce incorrect decoding.
-
-Examples of current behavior:
-
-- `@2+` is interpreted as Motorola instead of being rejected.
-- Numeric fields containing suffixes, such as `0junk` or `1junk`, are partially parsed and accepted.
-- `SG_ Value m1 : ...` is treated as an ordinary signal named `Value m1`, without multiplexing conditions.
-- A statement containing a tab after `SG_` is silently skipped.
-
-## Scope
-
-- Validate statement structure and require a nonempty signal name without whitespace.
-- Accept spaces and tabs between syntax elements.
-- Parse numeric fields completely, rejecting overflow and trailing characters; preserve support for fractional values and scientific notation in physical parameters.
-- Accept only byte order `@0` or `@1` and signedness `+` or `-`.
-- Require signal lengths within `1..64` bits.
-- Validate that the signal fits within the frame's declared payload length, using the appropriate Intel or Motorola bit traversal.
-- Reject NaN and infinite values for factor, offset, minimum, and maximum; require `minimum <= maximum`.
-- Explicitly reject multiplexing markers `M`, `mN`, and their combinations until multiplexing is implemented.
-- Preserve the error format `path:line: description`.
-
-## Acceptance criteria
-
-- [ ] Existing valid signal definitions continue to parse successfully.
-- [ ] Malformed and unsupported definitions stop parsing with a clear error.
-- [ ] Regression tests cover the cases above, numeric boundaries, and Intel/Motorola payload boundaries.
-- [ ] Existing parser and decoder tests pass.
-- [ ] README documents the new validation rules and limitations.
-
-## Out of scope
-
-Duplicate detection, multiplexing support, and `VAL_` support remain separate tasks.
-
-## Suggested branch
-
-`codex/validate-sg-definitions`