selectOneRadio - How to validate?

[Jeffrey Porter]

I have a radio button on my page created by a selectOneRadio tag. But I can submit the page without selecting an option. How to I get the radio button group to be validated?   I can see there is the tag “validator”, does this mean I have to implement a class to check that one option has been selected. Or is there a default class I can use?   Thanks Jeff     <h:outputLabel for="discoveryLocation" value="#{ebusiness_properties['NCM_label_discoveryLocation']}" />   <h:selectOneRadio disabledClass="bodyheading" enabledClass="bodyheading" id="discoveryLocation" value="#{nonConformingMaterial.discoveryLocation}" layout="lineDirection"  styleClass="selectOneRadio"> <f:selectItem itemValue="0" itemLabel="#{my_properties['NCM_label_location_0']}" />       <f:selectItem itemValue="1" itemLabel="#{my_properties['NCM_label_location_1']}"  />                 </h:selectOneRadio>