Extracting value of non-selected options from html <select> using PHP

I have开发者_StackOverflow an HTML that uses the following script as described in the first example here: http://www.mattkruse.com/javascript/selectbox/

I want to use PHP to extract the options that are in the right select box. How do I do that if they are not actually 'selected'?

Thanks,

I would just preselect them all before you submit the form. You can use a simple javascript function to preselect all the options in the list. You will need to make sure that the list supports multiple selected options.

Another way would be to just submit them all in a hidden form tag delimited somehow.