Undocumented BGP Neighbor command

Hello Guys,
i was doing a bgp config this morning and i stumbled by accident on the
following un-documented bgp neighbor command. Does anyone know what exactly it
does and in what scenario can one apply it?
i am using dynamips on a 3640 router running adv-ent IOS Version 12.4(23)
here is the output:

R4(config-router)#neighbor 22.22.22.22 up ?
  Async Async interface
  BVI Bridge-Group Virtual Interface
  CDMA-Ix CDMA Ix interface
  CTunnel CTunnel interface
  Dialer Dialer interface
  FastEthernet FastEthernet IEEE 802.3
  Lex Lex interface
  Loopback Loopback interface
  MFR Multilink Frame Relay bundle interface
  Multilink Multilink-group interface
  Null Null interface
  Port-channel Ethernet Channel of interfaces
  Tunnel Tunnel interface
  Vif PGM Multicast Host interface
  Virtual-PPP Virtual PPP interface
  Virtual-Template Virtual Template interface
  Virtual-TokenRing Virtual TokenRing

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Received on Wed Mar 03 2010 - 04:16:50 ART