Looking in the system/helpers directory (and this probably applies elsewhere) I see that the function documentation is set above the
/** Form Declaration
*
* Creates the opening portion of the form.
*...etc.
*
*/
if ( ! function_exists('form_open'))
{
function form_open($action = '', $attributes = '', $hidden = array())
{....instead of above the actual function itself. I think this is a real shame because it means an IDE (netbeans in my case) can’t give me contextual docs other than method signature as I auto-complete a function name. I have to open the actual file to see anything else.
I wonder if this will be changed in future versions…