Boolean test - Mailing list pgsql-sql

Hi,

I can't see why my sql here is throwing an error,   SELECT    *   FROM    plan_template   WHERE    public = true;

The field public is 'boolean'

I've also tried :   WHERE    public = 'true';   WHERE    public = t;   WHERE    public = 't';   WHERE    public =
'Yes';

Can you offer some advice ?
Thanks
Rudi.