The primary structure used in this code is a Field.
Fields store gridded data and inherit from numpy's ndarray.

A Field can be
0d (value at a particular point), 
1d (along a line)
2d (frame, vts, or hts)
3d (x, z, and t all vary)

The member variables are
  xmin
  xmax
  zmin
  zmax
  tmin
  tmax

Field.plot() produces an interactive plot for exploration
Field.save() 
The methods are 

