See, first of all the ad_form api documentation
sepcifically
the part on available datatypes, available widgets, and form element parameters and values
Here is an example
ad_form -name myform -form {
{myelement:text(checkbox),multiple,optional {options { {One 1} {Two 2} } } }
}
The variable myelement will contain a list of values that where checked in the processing code block for ad_form (ie: on_submit, new_data, edit_data)
