This is a sub-release of SDML 3.0 (click on "3.0" in the release
browser for details of new features in this release).

This sub-release contains most of the features of 2.6, except for:

	a) symbol searching

	b) charts

This sub-release is the first that uses "virtual memory" for various
information generated during a simulation (including the contents of
databases). The idea is that information that is accessed rarely, if
at all, is written to a disc file while frequently accessed
information is retained in memory. Therefore, simulations should be
able to run for as long as required without using up any more memory
(causing paging etc.), as long as there is enough disc space. Some
fine tuning may be required to improve the efficiency of virtual
memory, but simulations should run roughly as fast as in earlier
releases of SDML.

Disposal policies are not provided, since virtual memory is a better
way of achieving similar results. However, they may need to be
resurrected in the future if shortage of disc space becomes a
problem.

The virtual memory implementation is not yet complete, so using this
sub-release may cause problems if meta-agents are used, or if
primitives such as "generatedInstance", or those for choices or user
requests, are used on a lagged database.