Question: Does SedonaDB support custom / alternative coordinate systems?

For example, if i wanted to define a 4d region called (fish, towel, mouse, alien) and there were floats for each of fish/towel/mouse/alien?

SedonaDB can decode PROJJSON and authority:code CRSes at the moment, although the underlying representation is just a string. In this case you might want something like CZBOND:999 or

{ "type": "EngineeringCRS", "name": "Fish, Towel, Mouse", "datum": {"name": "Wet Kitty + Mouse In Peril"}, "coordinate_system": { "subtype": "Cartesian", "axis": [ {"name": "Fish", "abbreviation": "F", "direction": "east"}, {"name": "Towel", "abbreviation": "T", "direction": "north"}, {"name": "Mouse", "abbreviation": "M", "direction": "up"}, ] } }

(Subject to the limitations of PROJJSON, such as a 4D CRS having a temporal axis and a limited set of acceptable "direction" values)