Architecture

Layers

1. Typed model — model.rs represents the mvdXML 1.1 document, templates, views, concepts, requirements, definitions, identities, and rule groups.
2. Codec — codec.rs performs bounded namespace/order/UUID preflight checks, typed deserialization, and deterministic serialization.
3. Rule language — rules.rs parses and evaluates parameter expressions and recursive TemplateRules using caller-owned values.
4. Validation — validation.rs indexes identities and graph relationships, then applies fixed-schema, cardinality, key/keyref, grammar, cycle, and business checks.

Dependency boundary

The crate depends on general Rust libraries for XML, serialization, regular expressions, errors, and UUIDs. It has no IFC dependency.

A complete IFC conformance tool belongs in a higher-level adapter:

IFC library ─┐
             ├─> application adapter ─> RuleValues ─> openbim-mvd evaluator
openbim-mvd ─┘

The adapter interprets template paths, traverses IFC data, selects exchanges, computes metrics, and aggregates concept results. openbim-mvd remains responsible only for mvdXML document semantics and evaluation of supplied values.

Invariants

• mvdXML 1.1 is the only claimed document version.
• Untrusted XML is budgeted before typed deserialization.
• Writing is deterministic but not lexical-lossless.
• Validation is fixed-format code, not a generic XSD engine.
• IFC graph traversal never hides behind document validation.
• Official standards payloads do not enter source, package, or Pages output.