plone.app.discussion/plone/app/discussion/contentrules.zcml

<configure
  xmlns="http://namespaces.zope.org/zope"
  xmlns:zcml="http://namespaces.zope.org/zcml">

  <!-- Content Rules events -->
  <configure zcml:condition="installed plone.contentrules">

    <interface
      interface="plone.app.discussion.interfaces.ICommentAddedEvent"
      type="plone.contentrules.rule.interfaces.IRuleEventType"
      name="Comment added"
      />

    <interface
      interface="plone.app.discussion.interfaces.ICommentRemovedEvent"
      type="plone.contentrules.rule.interfaces.IRuleEventType"
      name="Comment removed"
      />

    <interface
      interface="plone.app.discussion.interfaces.IReplyAddedEvent"
      type="plone.contentrules.rule.interfaces.IRuleEventType"
      name="Comment reply added"
      />

    <interface
      interface="plone.app.discussion.interfaces.IReplyRemovedEvent"
      type="plone.contentrules.rule.interfaces.IRuleEventType"
      name="Comment reply removed"
      />

  </configure>


  <!-- Content rules subscribers -->
  <configure zcml:condition="installed plone.app.contentrules">

    <subscriber
      for="plone.app.discussion.interfaces.ICommentAddedEvent"
      handler=".contentrules.execute_comment"
      />

    <subscriber
      for="plone.app.discussion.interfaces.ICommentRemovedEvent"
      handler=".contentrules.execute_comment"
      />

    <subscriber
      for="plone.app.discussion.interfaces.IReplyAddedEvent"
      handler=".contentrules.execute_comment"
      />

    <subscriber
      for="plone.app.discussion.interfaces.IReplyRemovedEvent"
      handler=".contentrules.execute_comment"
      />

  </configure>

</configure>