To extend (I think!) Stefano's point, before determining what the PoA is, you have first to be very clear about what you're attaching.  Just saying "the terminal" makes no sense, because different layers in the terminal's protocol stack attach to different places in the network.
For example, the PHY layer attaches to the AP, but the TCP layer attaches to the destination host.
Mike.
  
  
    -----Original Message-----
From: Stefano M. Faccin [mailto:stefano.faccin@NOKIA.COM] 
Sent: Friday, September 30, 2005 1:08 AM
To: STDS-802-21@listserv.ieee.org
Subject: Re: [802.21] [DNA] Prefix information for link 
identification in DNA
Yoshihiro,
I'm not sure why should restrict the term PoA to have only a 
L2 meaning as you suggest below. I think we should 
distinguish clearly between L2 PoA and L3 PoA. For me, the L3 
PoA is where the terminal gets IP conenctivity. E.g. for GPRS 
the L3 PoA is the IP link on which the GGSN is located. In 
L2, PoA is the point where the access-specific L2 connection 
terminates (e.g. an AP in 802.11).
Stefano