Hello -
There are various forms of the state space model in use.
The form of the state space model used by the STATESPACE procedure is based on Akaike and covers a specific formulation only.
The UCM procedure (http://support.sas.com/documentation/cdl/en/etsug/63939/HTML/default/viewer.htm#ucm_toc.htm) provides access to a more flexible approach, but is restricted to one dependent variable. The new SSM procedure (http://support.sas.com/documentation/cdl/en/etsug/63939/HTML/default/viewer.htm#ssm_toc.htm - experimental with 9.3) provides access to the broadest range of state space models (including multiple dependent) and extents the UCM procedure.
This new procedure is a much more powerful and general tool for state space modeling than the old STATESPACE procedure, in fact the STATESPACE procedure should now be considered somewhat obsolete and superseded by SSM.
You will find examples for UCM and SSM syntax in the respective chapters of documentation.
Hope that helps,
Udo