A Plot3D is a specialised form of Plot that provides facilities for producing 3D graphical output.
If a null Object pointer (AST__NULL) is given, a default 3-dimensional Frame will be used to describe the physical coordinate system. Labels, etc. may then be attached to this by setting the appropriate Frame attributes (e.g. Label(axis)) for the Plot.
The first triple of values should give the coordinates of the bottom left corner of the plotting volume and the second triple should give the coordinates of the top right corner. The coordinate on the horizontal axis should be given first in each pair. Note that the order in which these points are given is important because it defines up, down, left and right for subsequent graphical operations.
AST A Library for Handling World Coordinate Systems in Astronomy