The lengthMm field captures the longest dimension of an individual object in millimeters. Along with widthMm and thicknessMm, it builds a complete metric description of an artifact, which is standard practice for tools, sherds, and other measurable finds. It is optional, so bulk lots or unmeasured fragments can leave it blank. Because it is stored as a decimal, you can record sub-millimeter precision. Consistent metric recording makes the catalog usable for typological and statistical analysis.
Technical section
Data model, API, and internals — visible to developers.