Remark: this file will be replaced by an even better idea soon ...

Problem:

  File nets or other high traffic stuff of somewhat "lower" importance should
  be sent on your own costs only in specific events (to keep costs low) or if
  remote caller wishes to pickup them (his costs, his decision).
         
Solution:

  Binkley style outbound flow types:

    FLO / OUT = normal
    DLO / DUT = direct
    HLO / HUT = hold
    CLO / CUT = crash

  Binkley XE style outbound flow types for low priority (LP) stuff:

    KLO / KUT = Keep low priority stuff (like "hold", but EMSI flag driven)
    LLO / LUT = normal Low priority stuff (like "direct", but EMSI flag driven)
                          
  EMSI flag extension:

    PUL = Pick-Up Low Priority stuff
          This flag has to be specified ADDITIONALLY to other *Pickup* flags
          to request to get / announce to send LP stuff additionally AFTER
          "normal" stuff. It does NOT replace other flags.

    NPL = No-Pick-Up Low Priority stuff
          This flag has to be specified ADDITIONALLY to other *Pickup* flags
          to tell that you do NOT wish to get and you will NOT send LP stuff.
          It does NOT replace other flags.

    A system supporting PUL/NPL flags does send exactly ONE of these two flags.
    Systems not yet supporting this do not send any of these two flags:

    <none> = if a system does not specify NPL or PUL, behaviour concerning
             LP stuff should be like following:
             If remote system does not specify NPL (meaning that it either
             says "PUL" or says just nothing), then enable a "PUL simulation
             for callers". This "simulation" can be either continuously on,
             so that LP flavours are equivalent to direct/hold flavours or
             can be driven by an event flag that is switched on in a low-tariff
             event, so that they get their files cheap, too (what's cheap is
             in this case defined by CALLED system because CALLER's system is
             obviously unable to decide).
             
    PUL / NPL flag is chosen e.g. on an event driven basis or manually.
    
  System behaviour:

    Inbound call:
    
      If PUL flag is presented in EMSI handshake by CALLING system, CALLER
      requests to enable LP flow file processing on the CALLED system and wants
      to get all stuff of this flavour after all other stuff of other flavours
      (if any). Also, it announces sending his own LP stuff.
      
      There might be reasons for the called system NOT to satisfy a PUL
      request made by the caller, e.g. because it is itself doing anything
      important and does not want to be busy with inbound callers for a longer
      time now (this has to be coordinated among the sysops). In this case,
      CALLED system sends back a NPL flag, telling the caller that his
      PUL request will NOT be satisfied and that caller shall NOT send his
      LP stuff, too (at least not if this would make the session last longer).
      If PUL will be satisfied, CALLED system sends back a PUL flag.
  
      If NPL flag is presented in EMSI handshake by CALLING system, CALLED
      system will ignore (= keep) any LP flavour stuff and also send back a
      NPL flag. CALLING system won't send any LP stuff, too.
      

    Outbound call:
      
      If PUL is active, it is sent in EMSI handshake packet by the CALLER
      to the CALLED system, announcing that CALLER
        a) will send LP stuff (if any) to CALLED system except if CALLED
           system answers with a NPL flag.
        b) wants to get LP stuff from CALLED system
        
      If NPL is active, it is sent in EMSI handshake packet by the CALLER 
      to the CALLED system, announcing that CALLER
        a) will NOT send LP stuff to CALLED system
        b) does NOT want to get LP stuff from CALLED system
      

Problem:

  You want to get out some stuff IMMEDIATELY overriding any cost restrictions.
  
Solution:

  Extended Binkley XE style outbound flow types:

    ILO / IUT = immediate (similar to "crash", but no cost restriction)
    

  
