parsing select multiple="multiple"

I am capable with <select name="DPRpriority">. (I suppose I did it correctly? :p ) But I haven't the first clue how to parse a <select multiple> and multiply select name="DPRtype". Would anyone give me a couple of clues please? :) Thanks, John

           Priority:
           <select name="DPRpriority" form="DPRform">
             <option value="1" <?php if ($_POST["DPRpriority"] == "1") {echo "selected";} ?>>1</option>
             <option value="2" <?php if ($_POST["DPRpriority"] == "2") {echo "selected";} ?>>2</option>
             <option value="3" <?php if ($_POST["DPRpriority"] == "3") {echo "selected";} ?>>3</option>
             <option value="4" <?php
             if (empty($_POST["DPRpriority"])) {echo "selected";}
             if ($_POST["DPRpriority"] == "4") {echo "selected";} ?>>4</option>
           </select>

           <select multiple="multiple" name="DPRtype" form="DPRform">
             <option value="1. Crimes Against Persons">1. Crimes Against Persons</option>
             <option value="2. Disturbances">2. Disturbances</option>
             <option value="3. Assistance / Medical">3. Assistance / Medical</option>
             <option value="4. Crimes Against Property">4. Crimes Against Property</option>
             <option value="5. Accidents / Traffic Problems">5. Accidents / Traffic Problems</option>
             <option value="6. Suspicious Circumstances">6. Suspicious Circumstances</option>
             <option value="7. Morality / Drugs">7. Morality / Drugs</option>
             <option value="8. Miscellaneous Service">8. Miscellaneous Service</option>
             <option value="9. Alarms">9. Alarms</option>
           </select>