On Tue, 08 Mar 2016, Stephen Hurd wrote to mark lewis:

 SH> There is no documentation I could find on how to set the cost 
 SH> value of a packet...

i don't see anything about a cost field in PKT headers so i'm unsure what you
mean byt the "cost value of a packet"...

 SH> and the individual messages in the packet don't have a cost.

they do have a cost field that originates from the stored message format (aka
MSG)...

 SH> There's not even any documentation of what the cost represents.

all i see is "in lowest unit of originator's currency" and the only thing i can
fathom that would be related to that is the cost of transporting that single
message from the current system to the next system... especially in light of
this all having been developed using POTS connections which were not cheap...
it was a feature whereby the operator could specify in their mail events that
messages with a cost <= X could be transmitted during eventA and messages with
a cost value greater than X would be held for another event which would qualify
them for transmission...

 SH> I could add that it's the expected cost the sender bears for
 SH> delivery of the packet,

yes...

 SH> but it's not clear if it's sender costs, receiver costs,

the sender has no clue what the receiver's cost is...

 SH> or the sum of both.  Without any clear reference for what that 
 SH> value should be, I can't write useful documentation on it... I 
 SH> mostly just copied the FTS-0001 information there.

i understand... i did find one portion in FTS-0001 that looked kinda familiar
with regard to the verbal wording of the layout ;) 

 > if you and i are linked, if my system places a value in the cost 
 > field of a packed message, what is your system supposed to do with 
 > that cost value when your system unpacks that message for processing?

 SH> Nobody knows because the meaning of that value was never 
 SH> documented. 

it always seemed obvious to me because of operator set values in mailers and
bbs packages and those being specifically referenced to be the cost of the POTS
connection...

eg: frontdoor's "minimum undialable cost" and the cost values listed in
FDNODE.CTL to call other country codes, areacodes or exchanges within the local
areacode...

 > zero it on  reception if it is not already zero... the receiving 
 > system may alter the value to fit their cost structure when they 
 > quality the mail for the next hop (eg: routed netmail being 
 > processed on an intermediate system)...

 SH> Except not all packed messages will necessarily have the same next
 SH> hop.

exactly why the cost is on a per message basis and not on a per packet basis...
that cost being taken into account when the message is packed for its next
hop... that cost determination coming from the operator maintained cost tables
used in the nodelist compilers and based on the country code, areacode or
exchange of the contact number the message is being packed to be sent to...

 SH> It could change that to the cost that was borne on receiving the 
 SH> packet, but I'm not certain how useful that information would be.

yeah, receiving costs has never been part of fidonet's things to worry about...
it was always the cost to send so as to prevent others from spending your money
instead of their own to send their netmail messages... that's why routing has
traditionally been destination HOST/HUB routing wherein the sender foots the
bill to deliver the message to the HOST or HUB of the destination system... it
wasn't until later that "sugardaddys" appeared and allowed others to route
outbound netmail through them to other systems...

)\/(ark