What are cyclide coordinates?

Some articles on coordinate, coordinates:

Green's Function For The Three-variable Laplace Equation - Rotationally Invariant Green's Functions For The Three-variable Laplace Equation
... exist in all of the rotationally invariant coordinate systems which are known to yield solutions to the three-variable Laplace equation through the separation of ... cylindrical coordinates spherical coordinates Prolate spheroidal coordinates Oblate spheroidal coordinates Parabolic coordinates Toroidal coordinates ...
List of Orthogonal Coordinate Systems
... The following coordinate systems all have the properties of being orthogonal coordinate systems, that is the coordinate surfaces meet at right angles ... Orthogonal coordinate systems Two dimensional orthogonal coordinate systems Cartesian coordinate system Polar coordinate system Parabolic coordinate system Bipolar coordinates Hyperbolic ...