question about Client-type OPN Msg

["sunjian" <jians@huawei.com>]

In the COPS protocol RFC2748
======================================================
3.6 Client-Open (OPN)  PEP -> PDP

   The Client-Open message can be used by the PEP to specify to the PDP
   the client-types the PEP can support, the last PDP to which the PEP
   connected for the given client-type, and/or client specific feature
   negotiation. A Client-Open message can be sent to the PDP at any time
   and multiple Client-Open messages for the same client-type are
   allowed (in case of global state changes).
        <Client-Open>  ::= <Common Header>
                                        <PEPID>
                                        [<ClientSI>]
                                        [<LastPDPAddr>]
                                        [<Integrity>]
=====================================================

It is said that:
 "A Client-Open message can be sent to the PDP at any time
   and multiple Client-Open messages for the same client-type are
   allowed (in case of global state changes)."

The question is :
1. What's the mean of "in case of global state changes"
    Does there some examples of "case"?
    Does the "state" refer to the established request handle?
    If it is, then why not do each request handle respectivly just as the
protocol said in  3.1 Request (REQ)  PEP -> PDP
"   Once a stateful handle is established for a new request, any
   subsequent modifications of the request can be made using the REQ
   message specifying the previously installed handle.
"

2.If it emphasize the word " global " then what's the following process will be?

1>
PEP                                                     PDP
OPN( ClientTypeA)->
         <-CAT(ClientTypeA )
OPN( ClientTypeA)-> ---------------------------At this point, what should the
PDP COPS do?

2>
PEP                                                     PDP
OPN( ClientTypeA)->
         <-CAT(ClientTypeA )
REQ( ClientTypeA handle 1)->
          <-DEC( ClientTypeA handle 1)
RPT( ClientTypeA handle 1)->

REQ( ClientTypeA handle 2)->
          <-DEC( ClientTypeA handle 1)
RPT( ClientTypeA handle 2)->

OPN( ClientTypeA)-> ---------------------------At this point, what should the
PDP COPS do?


Thanks

Sunjian