Geodesy / WGS 84 Knowledge Patch

Baseline: WGS 84 (G2139), ITRF2020, and PROJ through 9.3; covers WGS 84 (G2296), ITRF2020-u2024, PROJ 9.4 through 9.8.1, and related implementation details.

Use this patch

Before transforming or comparing coordinates, identify all of the following:

• Reference frame or datum realization, not only the label “WGS 84”, “ITRF”, or “ETRS89”.
• Coordinate epoch and parameter reference epoch for dynamic frames.
• Coordinate type, axis order, units, and dimensionality.
• Ellipsoidal, orthometric, dynamic, normal-orthometric, or tidal height semantics.
• Required accuracy, area of use, grid availability, and acceptable fallback behavior.

Then load the relevant reference below. Preserve explicit directions, signs, epochs, and units when transcribing transformation parameters.

Reference index