BT-XE style outbound, ideas for draft #2
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1. Basic idea

*.?LO / *.?UT
? := one character out of string ALL
ALL = "utsrqponmlkjihgfedcba9876543210" (31 chars total)
      chars "w".."z" are yet undefined and reserved

As BT-XE is a pure mailer (and does NO routing), there is (as far as Binkley is
concerned) no routing semantics contained in the outbound filenames.

As long as it does not conflict with BT-XE's settings / interpretation, other
software (like net, file and echomail processors) is free to define their own
semantics.

1.1 Simplyfication of "normal" flavour

BT yet uses *.?lo and *.?ut for outbound flow files and mail packets.
? = c means crash
? = h means hold
? = d means direct
? = f (flo) or o (out) means normal (you see that would be easier with "n")

New simplyfied BT-XE outbound style:

Same as above, but you also can use "n" for "normal" flavoured stuff ("nlo" and
"nut") - it will have the same default behaviour as "flo" and "out".

Software developers are encouraged to favour "n" in future, making things
easier for everybody. "flo" and "out" will be removed from default normal
sequence later.

1.2 "Direct" flavour semantics

BT-XE does not make any difference between direct and normal flavour.
"Direct" is yet supported as it is contained in the default Normal-Set, but
there is no special default treatment being different from "Normal" flavour.

Software developers should NOT use "direct" flavour and expect a special
default behaviour of BT-XE as "direct" will be removed from the default normal
sequence later.


2. General note on transfer behaviour (what stuff will be transferred)

Behaviour is primarily CALLER driven.
Only if caller is unable to do so (using software not supporting the new
methods described in this document), behaviour will be called-party event
driven (you may save some of the remote's cost by coordinating your settings
with the remote sysop).

Behaviour MAY also be restricted by called-party settings, but that should
only be done if REALLY necessary (e.g. not giving out echomail while netmail
hour).

3. Outgoing calls (own cost)

3.1 Outbound behaviour

Immediate-Sequence I = sequence of flavours to IMMEDIATELY call out
                       default: "i"
Crash-Sequence     C = sequence of flavours to call out if allowed
                       (CM / cost restrictions apply)
                       default: "c"
Normal-Sequence    N = sequence of flavours to send along with crash/immediate
                       default: "nfod" note: "fod" is supplied for
                                compatibility reasons only and may be removed
                                later from default.
Hold-Sequence      H = sequence of flavours to hold (send out only when being
                       called)
                       default: "h"
Leave-Sequence     L = sequence of flavours to totally leave alone (ignore)
                       default: ALL - I - C - N - H

3.2 Inbound behaviour

Pickup-Sequence    P = sequence of flavours to pickup from remote system
                       default: ALL

4. Incoming calls (other's cost)

4.1 Outbound behaviour

Remote will tell us his Pickup-Sequence using EMSI.

If not (old software calling), we use

Give-Sequence      G = sequence of flavours to give out if system doesn't tell
                       us
                       default: ALL - L

4.2 Inbound behaviour

We will use the Fetch-Set for incoming calls (this will be transmitted instead
of the Pickup-Set used with outgoing calls):

Fetch-Sequence     F = sequence of flavours to fetch from remote system on
                       incoming calls
                       default: ALL
                   
5. Emulation of old BT (and similar mailer) behaviour

I = ""                   [there is no "immediate" in old BT]
C = "c"                  [crash]
N = "fod"                [side effect: flo=olo=dlo, fut=out=dut]
H = "h"                  [hold]
L = ALL - I - C - N - H  [default L set]
P = ALL                  [default P set]
G = ALL - L              [default G set]
F = ALL                  [default F set]

Event examples:

Event ... I= N=FOD ... (quite same as old BT: no I/Immediate, no N/Normal -
                        only "direct" is maybe treated a bit different [?])
Event ... (no special settings will give you same behaviour as above, but
           with "immediate"(i) and "normal"(n) support)

6. Implementation details

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