Latitude of projection center (latitude of the point of projection for azimuthal projections) when subfield $a contains the text General vertical near-sided projection, Gnomomic, Orthographic, or Stereographic. Latitude of projection origin (latitude chosen as the origin of rectangular coordinates for a map projection) when subfield $a contains the text Albers conical equal area, Azimuthal equidistant, Equidistant conic, Lambert conformal conic, Oblique Mercator, Polyconic, or Transverse Mercator. Horizontal coordinate system. Map projection.
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