Seismic Unix has remained a stable, easy to install, and transportable package by following a few simple rules.

The first of these is that changing the SU header definitions is forbidden. The header structure looks deceptively simple, but contains a hidden trap, that it is possible to easily introduce a gap in the header that would render the SU data made under a new system mutually incompatible with that made by other versions of SU.

One of the stumbling blocks of older versions of SU was the use of subroutines written in different languages, such