Returns a string which identifies what authentication provider the commenter in context used to authenticate him/herself. Commenter context is created by either MTComments or MTCommentReplies template tag. For example, 'MT' will be returned when the commenter in context is authenticated by Movable Type. When the commenter in context is authenticated by Vox, 'Vox' will be returned.

Example:

    <mt:Comments>
      <$mt:CommenterName$> (<$mt:CommenterAuthType$>) said:
      <$mt:CommentBody$>
    </mt:Comments>