Info from:

http://www.w3.org/TR/html4/interact/forms.html

I am trying to create a multiple selectable SELECT menu however I also want to have categories in this menu, so the menu might look like:

Category 1
>> Select Option
>> Select Option
>> Category 2
>> >> Select Option
>> >> Select Option
Category 3
>> Selection Option

for example. Now this OPTGROUP would be perfect but it only works one level deep. Can anyone think of an alternative to this, perhaps using javascript which prevents the user from selecting the categories?