STLmuodot

STLmuodot is an open specification proposed to extend the traditional STL file format for three-dimensional models by incorporating form-related metadata alongside geometric data. It aims to preserve the simple geometry representation of STL while enabling additional descriptors that can inform downstream processes such as slicing, simulation, and archival.

The geometry section of STLmuodot remains compatible with existing triangle-based STL readers, using the same vertex and facet definitions. A separate metadata layer, which may be serialized as JSON or XML, accompanies the geometry and can describe surface classification, curvature hints, material intent, tolerances, units, and semantic labels for model parts. Implementations can opt to load only the geometry for basic rendering, while full pipelines may parse the metadata to drive automated workflows.

Development of STLmuodot has been led by a consortium of researchers and practitioners from additive manufacturing and computer-aided design communities. The specification emphasizes modularity, backward compatibility, and extensibility, allowing new metadata schemas to be defined without altering the core geometry format.

Adoption has been limited and primarily experimental. Support varies across software tools, and the lack of a widely accepted metadata schema has limited interoperability. Advocates contend that formal metadata can improve print reliability, traceability, and interoperability between design, simulation, and fabrication stages.

See also: STL file format; 3D printing; mesh formats; metadata in CAD.