# openbim-step
Generic ISO 10303-21 physical-file and ISO 10303-11 EXPRESS language infrastructure.
## Owns
- tokens, source spans, syntax diagnostics, and complete classic STEP string escaping;
- arbitrary-precision instance IDs, records, parameters, headers, and exchange sections;
- parser, deterministic writer, record partitioning, and incremental event sinks;
- schema-neutral EXPRESS declarations, type expressions, and parser diagnostics;
- the schema graph over those declarations: supertype chains, Part 21
positional attribute order, and defined-type alias resolution.
## Does not own
- application-schema registries, bundled schema artifacts, or schema-version policy;
- application model/value conversion or entity graph construction;
- domain/select resolution, validation, migration, or inference.
See sibling `PLAN.md` for active work.