It is explained in the config file.

#  The reply attributes sent to the NAS are
            #  usually based on the name of the user
            #  'outside' of the tunnel (usually
            #  'anonymous').  If you want to send the
            #  reply attributes based on the user name
            #  inside of the tunnel, then set this
            #  configuration entry to 'yes', and the reply
            #  to the NAS will be taken from the reply to
            #  the tunneled request.
            #
            # allowed values: {no, yes}


#  the PEAP module also has these configuration
            #  items, which are the same as for TTLS.


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