Business Rules - Cartography

This document lists the fundamental rules of the cartography domain, each identified by a unique BR-NNN code. Every rule is technology-independent and describes an invariant constraint on surveying, projection, georeferencing and publication of geographic data.

> Note: This is a technical-scientific surveying domain. The rules model the process of measurement, projection and validation of spatial data, not commercial transactions.

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BR-001 - Explicit reference system mandatory

Code: BR-001 Name: Every geographic datum must declare its reference system (CRS/EPSG) Description: A Map, a GeographicLayer or a Survey cannot exist without an explicit reference system identified by an EPSG code (e.g. 4326 for WGS84, 25832 for ETRS89/UTM32N). Coordinates without a CRS are ambiguous and unusable. Motivation: Prevent positioning errors due to misinterpretation of coordinates. Priority: CRITICAL Actors: Cartographer, GIS User Traceability: EPSG; ETRS89; WGS84; reproject-layer.md.

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BR-002 - Consistency between scale and precision

Code: BR-002 Name: The data detail must be consistent with the representation scale Description: A Map at a given MapScale (e.g. 1:25,000) has an implicit minimum positional accuracy (plottable error ≈ 0.2 mm × scale denominator). Features are not represented with precision higher than the scale allows. Motivation: Avoid attributing to the map a precision the data does not possess. Priority: HIGH Actors: Cartographer, Photo Interpreter Traceability: Scale; contour interval; produce-map.md.

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BR-003 - Survey validation before publication

Code: BR-003 Name: A Survey must be processed and validated before publication Description: Field data (GNSS points, LiDAR clouds, photogrammetry) must pass through processing and quality control (residuals, traverse closure, accuracy) before transitioning to published as a GeographicLayer or Map. Motivation: Ensure the geometric reliability of disseminated cartographic products. Priority: HIGH Actors: Geodesist, Cartographer Traceability: survey-lifecycle.md; RINEX; perform-survey.md.

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BR-004 - Traceability of datum transformation

Code: BR-004 Name: Every reprojection between datums must use a documented transformation Description: Conversion between reference systems (e.g. Roma40/Gauss-Boaga → ETRS89) must use a known transformation (e.g. 7-parameter Helmert, official grids) and record it, because different transformations produce discrepancies of several metres. Motivation: Make every coordinate reprojection reproducible and verifiable. Priority: HIGH Actors: Geodesist, GIS User Traceability: Helmert transformation; PROJ; reproject-layer.md.

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BR-005 - Georeferencing of geodetic points

Code: BR-005 Name: Every GeodeticPoint has declared coordinates, elevation and accuracy Description: A geodetic point (trig point, benchmark) records coordinates in the declared CRS, elevation (orthometric or ellipsoidal with the reference geoid) and estimated accuracy. The distinction between GPS elevation (ellipsoidal) and a.s.l. elevation (orthometric) is explicit. Motivation: Avoid confusion between elevation types that differ by tens of metres. Priority: HIGH Actors: Geodesist, Cartographer Traceability: Geodetic Vertex; geoid; GeodeticPoint entity.

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BR-006 - Officiality of toponyms

Code: BR-006 Name: OfficialToponyms come from authoritative sources Description: Place names shown on an official map derive from recognized toponymic sources (IGM, municipal registry); unofficial variants are distinguished. Modifying a toponym follows a registration process. Motivation: Ensure consistency and authority of cartographic toponymy. Priority: MEDIUM Actors: Cartographer, GIS User Traceability: Toponymy; IGM; OfficialToponym entity.

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BR-007 - Map versioning

Code: BR-007 Name: Every update of a published Map generates a new version Description: Corrections or updates of a published map produce a new tracked version (MapVersionReleased), keeping the previous version as a historical reference until deprecation. Motivation: Allow consumers to know which edition of the data they are working on. Priority: MEDIUM Actors: Cartographer, GIS User Traceability: map-updated (event); Map entity.

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BR-008 - Interoperability through standard formats and services

Code: BR-008 Name: Published data use standard formats and services (OGC) Description: A published GeographicLayer is exposed in interoperable formats (GeoJSON, GeoPackage, Shapefile, GeoTIFF) and/or standard OGC services (WMS, WMTS, WFS), with the declared CRS, to ensure cross-platform use. Motivation: Avoid lock-in and enable integration across different GIS tools. Priority: MEDIUM Actors: GIS User, Cartographer Traceability: WMS/WMTS/WFS; GeoJSON; GeoTIFF; BR-001.