You may also find some slightly more recent perspectives on time in the
on SAIF, which concluded in January 1995. See:
http://home.gdbc.gov.bc.ca/saif/ There are issues pertaining to tracking
objects over time as well as treating time as an integral part of space.
Adding time to the coordinate system may be worthwhile as an option; but
also of interest might be to add to a coordinate position an arbitrary
measure or specific structures to support linear referencing.
Another addition of big time interest would be coverage support;
this has yet to be finalized by OGC.