I believe it was abandoned in favor of analytic functions (or just
because of lack of interest from customers.) 8.1.7 docs still included
Time Series docs from 8.1.5 release, there were no updates to the
option nor to the documentation since 8.1.5, and the option was
removed from 9i.
Regards,
Vladimir M. Zakharychev
N-Networks, makers of Dynamic PSP(tm)
http://www.dynamicpsp.com