grammar #

In the C ABI #

Returned by all 19 per-format shared libraries — the ABI is uniform, so every clib can return it.

It arrives as the whole reply, not inside a diagnostic:

{"ok":false,"error":{"code":"grammar","message":"…"}}

This says your call was wrong, not your input. A library that read your input and decided it is outside the format replies {"ok":true,"accept":false} instead — a rejection is an answer, and it carries no code from this namespace. If you are here because a parse "failed", check which of the two you actually got before treating it as an error.

The five-symbol ABI and its guarantees are in tabnas.h; the decision behind it is ADR-12 in the admin repository.

What to do with it #

1. Check the message beside the code: unlike a parse diagnostic it is not templated, and for a call-level failure it usually names the argument at fault.
2. Confirm the call shape against tabnas.h. Lengths are explicit byte counts and buffers are not read as NUL-terminated strings; every returned char* must be released with tabnas_free, and every handle with tabnas_grammar_free.
3. If you are writing the binding rather than using one, the four maintained loaders (Rust, Python, JVM, .NET) already implement this contract and are graded against every clib in the fleet.