{ }
as in the example
{ name[:flag,flag,flag] default }
That is, it is formatted as a two element tcl list where the first element is name:flag and the second element is default.
ad_page_contract { uses bind variables in a query @author Matthew Smith } { user_id:integer "1" } -properties { users:onerow }
set query " select first_name, last_name from ad_template_sample_users where user_id = :user_id"
db_1row users_query $query -column_array users