But I think the -property block of ad_page_contract doesn't do too much enforcing. If you use a db_multirow and leave that out of the -property block, the page will still work.
Also, you are not passing any data to the adp file. In the templating system, the file with the adp ending is actually a template that is compiled into tcl code and executed after the tcl file is sourced. I believe the term used in the templating system documentation is 'preparing datasources'. This is what happens in the tcl file.
