SB10L18 is the SIO joint Vs/Vc mantle model.
Vp was reconstructed from Vs and Vc.
This model is a 10 degree equal area 
block model (lateral parameterization) and has 
18 layers (radial parameterization).

The model has 4 files (three binary!!). block.desc is the model 
descriptor file (ascii), block.sb10l18.x (with x being
c, p or s) is the binary model for bulk sound speed, Vs
and Vp (use option binary for ftp!).

There's currently no other comprehensive README file that could
help to decipher the binary file, but in principle the
only thing needed is the fortran subroutines in file sb10l18.subs.f.
This file include everything necessary to handle the model.
there are a couple of lines that could go into a main calling routine.

There are two versions:
sb10l18-intel.tar.gz is for all computers that use little-endian
binary data. This includes all computers with an intel chip.

sb10l18-bigend.tar.gz is for all computers that use big-endian
binary data. This includes older PowerMac computers and Sun
workstations.

Use gunzip and tar to extract a folder with the following files:
README.sb10l18
block.desc.sb10l18
block.sb10l18.c
block.sb10l18.p
block.sb10l18.s
sb10l18.subs.f
sb10l18.eps.gz

In addition to the two compressed files, sb10-maps.tar.gz is a compressed
tar file of a folder with maps in long lat value format. The number in the 
file name denotes the center depth of the layer.

Finally, vpvs.fig??.eps are postscript version of some of the figures
in Masters et al. (2000).

Send questions to glaske-at-ucsd.edu

REFERENCE:
----------
Masters G., Laske, G., Bolton, H. and Dziewonski, A., 2000.
"The Relative Behavior of Shear Velocity, Bulk Sound Speed, and Compressional
Velocity in the Mantle: Implications for Chemical and Thermal Structure"
in: S. Karato, A.M. Forte, R.C. Liebermann, G. Masters and L. Stixrude (eds.)
"Earth's Deep Interior", AGU Monograph 117, AGU, Washington D.C.