Question : multiple nomatch rules ?

Hi,

I have the following grammar :

<grammar root="command">
<rule id="command" scope="public">
            <item><ruleref uri="#action"/></item>
            <item><ruleref uri="#contact"/></item>
 </rule>

<rule id="action">
      <one-of>
             <item>call<tag>action="call"</tag></item>
             <item>find<tag>action="find"</tag></item>
             <item>search<tag>action="spell"</tag></item>
       </one-of>
  </rule>

<rule id="contact">
      <one-of>
             <item>john<tag>contact="john"</tag></item>
             <item>georges<tag>contact="georges"</tag></item>
             <item>sandra<tag>contact="sandra"</tag></item>
       </one-of>
  </rule>
</grammar>


I'd like to know if it's possible to write 2 <nomatch> rules :
- one to say "Sorry this contact doesn't exists" if the user said for example "call peter"
- one to say "Sorry i don't understand" if the user said a real un-understable sentance.

because actually, i have the message "Sorry i don't understand" even if the rule "action" matches something, but i'm unable to catch it.

Thanks for your help,

    Yahn Teisseire