0033: Content-format model meaning

Context

A Full model assessment must establish the content-format declaration’s modeled meaning independently of a sample. Grammar and positive registry membership do not establish arbitrary media parameters, their absence or ordered coding meaning. For example, a registered multipart name cannot conceal missing knowledge about its required boundary parameter. The existing expanded assessment in ADR 0029: Content-format declarations and recorded registry guidance intentionally advertises only grammar and recorded guidance.

Decision

Keep ExpandedContentFormat unchanged. FullBaseline M024 additionally establishes complete recorded numeric CoAP tuples and a small explicit media-rule set: parameterless JSON and CBOR, one no-effect JSON charset, and the plain-text US-ASCII default or one UTF-8/US-ASCII charset. Other media-specific rules, parameters and duplicate parameters remain Unassessed. Missing or withheld registration evidence remains Undetermined. The content-format contract pins these distinctions and their primary RFC sources.

Positive explicit coding tokens identify transformations applied in their stated order, including repeated occurrences, under RFC 9193 Section 3. Absent coding means no transformation. Explicit reserved identity remains unavailable; do not import HTTP negotiation semantics as an SDF error. Numeric declarations designate complete registered content-type/coding tuples, without a second unrelated registry query or payload interpretation.

Use the existing charged borrowed grammar/registry replay, with a private meaning module and no public syntax tree. Preserve every authored string and origin. Record actual admitted consultation as content-format-model-meaning/1, even when optional findings are omitted. Unsupported semantic observations occur before finding-retention decisions. All scans, tuple accesses and parameter comparisons consume the original shared work allowance.

The complete Full report can carry ten interpretation IDs, beyond the registry module’s four, including copied-reference-relocation/1 from ADR 0036: Copied reference relocation. Requalify both complete report generations, interpretation Vec growth, registry records, retained-result fallback and optional omission against the original reserves. The compiled backend fits those reserves; qualification checks the combined graph rather than assuming a free fourth array slot. This follows ADR 0009: Bounded processing and reporting.

Considered Options

Completing every registered parameterless media name would conceal required parameters outside the known rules. Inferring arbitrary media semantics from recorded CoAP tuple spellings would need additional normalization and matching rules. Acquiring every registry template would broaden dependencies and trust without delivering a proportional general interpreter. A public parser tree would force callers to rebuild conclusions. Payload decoding and protocol bindings are outside model declaration meaning. Increasing reserves before qualifying the compiled maximum graph would hide an avoidable ownership cost.