Design rules

A statement that a design, as written, meets a published physical, biological or licensing condition under which it is unlikely to work or unlikely to ship. Appendix C.5 carries fifteen such rules under the DFM prefix. Each finding carries a code, a fixed severity, a message naming the numbers it computed, a remedy, and the literature source the threshold rests on.

Yes. A design-rule finding is advisory with respect to conformance. A package MAY conform to WWD and still fail every rule in the table, because WWD does not own the physics. An implementation MUST NOT report a DFM code as a conformance error, and MUST NOT suppress one because the package is otherwise valid. muscle-strip-highstiff.wwd is the case: it validates with zero errors and zero warnings and disposition pass, and the same run reports DFM-001 and DFM-012.

A severity written ERROR to WARNING means the condition holds against the conservative end of a cited range and may not hold against the optimistic end. DFM-001 is the only graded rule: the oxygen diffusion depth in the literature is 100 to 200 um, a range rather than a number. A graded rule MUST report which end of the range its severity was decided against, and MUST report the margin at both ends. Collapsing the range to one number would assert a precision the literature does not have.

Two warnings. DFM-001, because the 300 um thickness leaves about 100 um of core starved under the conservative 100 um diffusion depth while the optimistic 200 um depth covers it, with the sources Rouwkema 2009 Biotechnol Genet Eng Rev 26:163 and Rafique 2023 PMC10295847. DFM-012, because the skeletal muscle myoblast entry carries no licensing block, so commercial derivative rights are undeclared, sourced to NEURONTILE-PRODUCT-SPEC.md sec.5 Q1.

It reads the number if there is one and declines to evaluate if there is not. DFM-005 extracts a value and a unit from wwd:ecm_stiffness. A quantity string such as "12 kPa" yields both. A field object backed by a mesh attribute, as in graded-strip.wwd, carries a store, an array and an interpolation rule and no single number, so the extraction returns nothing and the rule does not run. The same holds for lengths: an unrecognised unit or a bare number returns nothing rather than a guess, and DFM-016 reports that the dimension could not be read and names the axis the diffusion check used instead.

In the design, under §7.14. A design MAY declare rules: named deterministic assertions over values in the package. Every rule MUST have an identifier and an assertion, MUST declare a severity of error or warning chosen by the producer, and MUST declare inputs that each resolve to a value in the package. The assertion MUST be an expression under the Core expression profile and MUST evaluate to a boolean. A rule that cannot be evaluated MUST be reported as an error regardless of its declared severity. A consumer MUST evaluate every declared rule and MUST NOT suppress a Core diagnostic because a producer rule passed.

DFM-001 and DFM-012 on every muscle strip package, because all of them are 300 um thick with no declared transport and none carries a licensing block. DFM-009 in addition on muscle-strip-designed.wwd, graded-strip.wwd, bioprinted-strip.wwd and pinwheel-study.wwd, which carry a critical response criterion and no yield block. DFM-010 on pinwheel-study.wwd, once per component with no validity window. On neurontile-asbuilt.wwd, DFM-012 twice: the glutamatergic neuron entry declares rights unknown, and the astrocyte entry carries no licensing block.

One does. DFM-009 reads the yield block of the results document and reports critical response criteria that have no yield statement. The remaining rules read the design document: component kind, dimensions, fields, interfaces, biology, shipping and validity window, and the acceptance criteria the design declares.