OrbData and OrbData5 are two variants of the same program;
its purpose is to fill in required nodal data for each node of
a Shells finite-element grid (.feg) file, prior to using that grid
in Shells dynamic simulation experiments.

(Note that FiniteMap should be used to prepare maps of the results, 
to check for any errors or unexpected features!  Another option is
to inspect the values with OrbWin, using the Edit/Elevation...
command together with the View/ZoomInOut command.)

OrbData is the older program, which we used for all Shells models
PRIOR to the Earth5 models of Bird et al. [2008; J. Geophys. Res.].
It reads only 2 or 3 gridded data (.grd) files:
   -elevation/topography/bathymetry (e.g., ETOPO5 from NOAA/NGDC)
   -heat-flow (e.g., kriged from Pollack et al. [1993; Rev. Geophys., 31(3), 267]
   -age of seafloor (e.g., Mueller et al. [1997; J. Geophys. Res., 102(B2)])
    [Note: This last .grd file is optional.  However, it is strongly
     recommended to use seafloor age if your model includes oceanic lithosphere.]
OrbData then computes crustal thickness and mantle lithosphere thickness
based on assumptions of local isostasy and steady-state geotherm,
respectively.

The use of OrbData is described in my online tutorial, beginning with
Step 12.  It also requires a short file of physical parameter values 
(e.g., rock densities, thermal conductivities, radioactive heat production)
in the same format as that read by Shells.

OrbData5 is the newer program, and it reads 5 .grd files:
   -elevation/topography/bathymetry (e.g., ETOPO5 from NOAA/NGDC)
   -heat-flow (e.g., kriged from Pollack et al. [1993; Rev. Geophys., 31(3), 267]
   -age of seafloor (e.g., Mueller et al. [1997; J. Geophys. Res., 102(B2)])
   -thickness of crust (e.g., CRUST2 model of Bassin et al. [2000; Eos, 81, F897])
   -S-wave travel-time anomaly in the upper mantle, above 400 km depth
      (e.g., S20RTS model of Ritsema & Van Heijst [2000; Science Progress, 83, 243])
Like OrbData, it also requires a short file of physical parameter values in
the same format as those read by Shells.
For a description of the various algorithms OrbData5 uses, see our latest paper
[Bird et al., 2008; J. Geophys. Res.] on the Earth5 model set.
Basically, we incorporate the 2 additional seismic constraints by adding two
adjustable parameters at each node: 
   -density anomaly of the lithosphere of compositional origin;
   -extra quadratic curvature of geotherm due to transient cooling/heating.
and these extra values are incorporated into the .feg file, where they can
be displayed with FiniteMap (but NOT OrbMapAI) or with OrbWin.

Examples of these gridded data files are now to be found in 2 folders:
/oldFTP/neotec/Shells/Earth2/global_GRDs/ (and/or)
/oldFTP/neotec/Shells/Earth5/global_GRDs/

Peter Bird
UCLA
2007.10.10