The SELECT, OPTGROUP, and OPTION elements

 <SELECT multiple size="4" name="component-select">
      <OPTION selected value="Component_1_a">Component_1</OPTION>
      <OPTION selected value="Component_1_b">Component_2</OPTION>
      <OPTION>Component_3</OPTION>
      <OPTION>Component_4</OPTION>
      <OPTION>Component_5</OPTION>
      <OPTION>Component_6</OPTION>
      <OPTION>Component_7</OPTION>
 </SELECT>

<SELECT name="ComOS">
     <OPTION selected label="none" value="none">None</OPTION>
     <OPTGROUP label="PortMaster 3">
       <OPTION label="3.7.1" value="pm3_3.7.1">PortMaster 3 with ComOS 3.7.1</OPTION>
       <OPTION label="3.7" value="pm3_3.7">PortMaster 3 with ComOS 3.7</OPTION>
       <OPTION label="3.5" value="pm3_3.5">PortMaster 3 with ComOS 3.5</OPTION>
     </OPTGROUP>
     <OPTGROUP label="PortMaster 2">
       <OPTION label="3.7" value="pm2_3.7">PortMaster 2 with ComOS 3.7</OPTION>
       <OPTION label="3.5" value="pm2_3.5">PortMaster 2 with ComOS 3.5</OPTION>
     </OPTGROUP>
     <OPTGROUP label="IRX">
       <OPTION label="3.7R" value="IRX_3.7R">IRX with ComOS 3.7R</OPTION>
       <OPTION label="3.5R" value="IRX_3.5R">IRX with ComOS 3.5R</OPTION>
     </OPTGROUP>
 </SELECT>