Here: Standard parallels at 60° North/South in order to get a map that is exactly square.
I added this specific configuration in March 2020. I’ve never seen it before, but it’s not unlikely that someone somewhere did use it before.
Jump to different depiction of this projection:
Specified in [square brackets]: Actual size of the projection
(minus the black or white background). When marked with [≈], sizes with and without
background are approx. the same.