Double Stereographic projection is a variation of Stereographic projection and is also used to represent polar areas. Points are projected from a position on the opposite side of the globe onto a plane tangent to the Earth. Double Stereographic is the term used in Esri software for Oblique Stereographic case (EPSG code 9809) which uses equations from the EPSG. In contrast, the Stereographic case uses the USGS equations of Snyder. The Double Stereographic projection is used for large-scale coordinate systems in the Netherlands and New Brunswick.
All meridians are straight lines or circular arcs.
All parallels are straight lines or circular arcs.
Oblique aspect: the parallels are concave toward the the poles with one parallel being a straight line.
Equatorial aspect: parallels curve in opposite directions on either side of the Equator
Graticule intersections are 90 degrees.
Scale increases in movement from the center.