Reference

Reference datasets and tables — curated from authoritative primary sources (ISO, NGA, USGS, IANA) and released under CC BY 4.0. Every value is cited to its original spec.

• Coordinate Format Cheatsheet

  The eight common coordinate formats used on the modern web — decimal degrees, DMS, DDM, UTM, MGRS, Plus codes, Geohash, and Maidenhead — with the Empire State Building in every format, valid ranges, precision per digit, primary specifications, and when to use each.

• WGS 84 Parameters

  The four defining parameters of the World Geodetic System 1984 (semi-major axis, reciprocal flattening, geocentric gravitational constant, mean angular velocity), every derived ellipsoid value, normal gravity at equator and pole, and the realization history from original 1987 through WGS 84 (G2139) 2021. Cited to NGA STND 0036 and NIMA TR 8350.2.