Container geometry and payloads

Three, and they compose. A component MAY declare named dimensions under component.dimensions, a map of name to quantity string or dimension object. A component with geometry MUST state an axis-aligned bounding box in its component frame, derived from or consistent with the authoritative geometry within declared tolerance. A component MAY declare component.geometry, an object naming a delegated asset, its format and whether it is authoritative. A spatial component MUST reference authoritative geometry or explicitly declare geometry omission and rationale. Under the conformance checker, a spatial component with neither geometry nor dimensions is reported as not manufacturable.

A named dimension has exactly two spellings. The simple spelling is a quantity string and means a designed nominal dimension with no stated tolerance. The rich spelling is an object carrying nominal and, as applicable, tolerance, targets, causal_role, provenance, imposed_by, observation_activity and derived_from. Upgrading from the string to the object MUST NOT change the dimension name, its position in the document, or the meaning of its nominal value. A dimension in the object spelling MUST declare a nominal quantity, a causal role and a provenance class. A dimension referenced by an interface or constrained by an acceptance criterion MUST declare a tolerance or a permitted interval, and the string spelling cannot carry one.

An asset, a format and an authoritative flag. The reference schema requires asset and format, and closes format to 3mf, step, stl, gltf, glb, vtu, svg and dxf. An authoritative geometry asset MUST identify its media type and applicable format version when known. A package MAY contain more than one geometry representation, and exactly one MUST be designated authoritative for each purpose requiring geometric truth. A preview or visualization mesh MUST NOT be assumed authoritative unless explicitly designated. Derived geometry MUST identify the source geometry and derivation activity.

Every internal ZIP entry except mimetype and wwd/manifest.json MUST have exactly one manifest file record, and every record MUST identify logical name, media type, byte length, integrity and role. The byte length MUST equal the exact number of uncompressed octets. The integrity value MUST use the textual form sha256- followed by the Base64-encoded SHA-256 digest. A consumer MUST verify manifest byte length and integrity before using an internal asset for manufacture, acceptance, or simulation, and MAY defer verification until the asset is first used. A package whose internal asset fails integrity verification MUST be rejected for all conformance classes requiring that asset. The package MUST NOT contain unmanifested payload files.

STL MAY be used for surface shape but MUST NOT be used as the sole carrier of units, topology semantics, regions, or interfaces. When STEP semantics are available, they SHOULD be retained rather than flattened to STL. A delegated asset MUST identify its coordinate frame or provide a complete transform into a WWD frame, and MUST identify units not already normatively defined by its format, so an STL asset carries those declarations in the WWD document rather than in the file.

3MF MAY carry additive-manufacturing or implicit geometry, and 3MFBio MAY carry printer-process metadata but MUST remain delegated. Printer-process metadata such as 3MFBio MAY be referenced as a delegated asset or extension, but MUST NOT be treated as the WWD core architecture. In bioprinted-strip.wwd the 3MF part is the authoritative geometry and also the fabrication protocol reference, with protocol_format 3mf. The design document keeps the biological identity, the property fields, the causal roles, the interfaces and the acceptance criteria, and surfaces one delegated control, print nozzle temperature, with imposed_by pointing into the delegated part at process/print-job.3mf#extruder-1.

Every component with spatial content MUST define one canonical component frame. The component frame MUST be right-handed Cartesian. Its axes MUST be ordered x, y, z. Its origin MUST be explicitly defined relative to the component geometry or interface datum. Each spatial axis MUST have a physical length unit, and all three SHOULD use the same one. A component frame MUST NOT infer anatomical directions from axis letters, and an anatomical interpretation MUST be an explicit annotation using UBERON or a domain profile. An additional frame MUST have an identifier, origin, ordered axes, handedness, and axis units, and a rigid or affine relationship to another frame MUST state a homogeneous 4 by 4 transform mapping child coordinates into the named parent.

In every Core scalar-or-field slot. A bare JSON number MUST NOT serve as a dimensional quantity, and the validator reports C02_BARE_NUMBER. A tolerance written as a bare number is reported as Z05_BAD_TOLERANCE. Dimensionless values MUST use unit 1 and fractions MUST use unit 1, so a dimensionless slot still carries a unit string. Units MUST use UDUNITS-2-compatible unit strings unless a delegated payload has its own normative unit vocabulary, and a unit that is not an accepted spelling of a registered term canonical unit MUST be refused even where a conversion factor exists.

Through the mesh_attribute backing. It MUST reference a delegated mesh and a named attribute or accessor, MUST declare association as node, cell, face, edge or quadrature, and MUST declare the interpolation rule. The value count and component count MUST agree with mesh topology and declared association. The field frame MUST be consistent with the mesh frame or provide an explicit transform. In graded-strip.wwd the ecm_stiffness field names store fields/stiffness.vtu, array stiffness, association node and interpolation shape_function, and the payload is manifested with media type application/vnd.vtk.unstructured-grid+xml. The validator counts the mesh points and the array values and reports F12_COUNT_MISMATCH when they disagree.

It reads a delegated mesh only far enough to count points and cells and to locate the named array. It does not parse mesh geometry, validate element connectivity, or interpret the numbers, because those belong to the delegated format and its own tools. It does not recompute a bounding box from an asset, so the section 5.4 obligation that geometry and named dimensions agree within tolerance is checked against the delegated file by the parties exchanging it.