.\" @(#)domains	1.3	12/3/92
.H1 "Multi-Domain Universes"
.pp
The domain of an application is set using the pigi ``Edit:edit-domain''
or ``d'' command.  This command causes a checklist to appear
listing all domains currently linked into the system.
All examples in the SDF Demo palette are one-domain applications,
using only SDF.  Several examples of multi-domain applications
can be found in the DDF and DE Demo palettes.
It is instructive to explore these applications, using the edit-domain
command at all levels of the hierarchy to see what domains are used.
.pp
Recall that a
.c Wormhole
in \*(PT is a block that has a different domain on the outside than
on the inside.
.IE "wormholes in pigi"
.IE "domains in pigi"
In pigi, wormholes look exactly like galaxies.
The only difference is that the domain is different on the inside
than on the outside.
.pp
To build multi-domain applications, it is necessary to understand
the models of computation in each domain, to ensure that application
will behave consistently at the domain boundaries.
For this, it is necessary to refer to the domain documents,
included in the Almagest.
