SELECT tags in PHP, addressing selected options

I'm having a problem with PHP/HTML. My problem is this: I have a <SELECT NAME = "list" MULTIPLE> list box in an HTML form. In that, obviously, users can select multiple choices. They click the submit button. The action for the form is to submit it to a PHP page which will list all of the selected options, which are <OPTION>Choice1</OPTION>. But how? I can't figure out how to address those selected options. Would it be $Choice1? Should I include a NAME attribute? Does anyone know how to address these options? Liam Gibbs