The OYSTER environment, i.e. the capability to handle interferometer
configurations, compute 
-coverages and other astrometric circumstances,
to compute model visibilities, and do plotting, makes it interesting as a
tool to handle interferometers other than the original target NPOI too.
Beginning in OYSTER version 6, the code was streamlined by concentrating interferometric configuration control in a single procedure container file, oyster.pro.