DDE Specification for WinPack V6.2
----------------------------------

(You must know something about DDE to understand this!)

Server Name: Packet

Topic Name: WinpDDE

Item Names: txtDDE
            labDDE2        (not supported before V6.2)
            labDDEStatus   (not supported before V6.2)

txtDDE is retained to maintain compatibility with the DDE support in
WinPack before V6.2. It is recommended that any new applications
using DDE links should use labDDE2 and labDDEStatus.

Item Usage
----------
Links can be established to all three items to allow your program to
be notified when the data in the items changes. You can use
automatic, notify or manual links.

txtDDE
------
This item receives all monitored data when WinPack is not connected
and all connected data. If WinPack is in BPQ mode or host mode,
monitored data is not sent whilst a connection is in progress, even
though it is available. Data is not sent if WinPack is either
involved in a Yapp transfer or uploading/downloading compressed
mail. The item is cleared before it is updated, so your program will
see two transactions - one with an empty string - each time txtDDE
is updated. This is done because if the item is updated with
identical data, VB does not trigger a DDE transaction, so if an
ASCII file transfer was occurring in which two successive lines were
identical, the client application might only see one line.

labDDE2
-------
This item behaves exactly like txtDDE, except that the problem of
making sure the client sees every update is handled differently. The
first character of the data is alternately '0' or '1'. You should
discard the first byte when the data is received.

labDDEStatus
------------
Every time WinPack's connected status changes, this item is updated
with the connected status information - see below.

Link Execute
------------
If an execute transaction is sent to the server, the command string
is normally sent to the TNC. There are two exceptions:-

If the command string is "<ESC>[STATUS]" then txtDDE is updated with
connected status information.

If the command string is "<ESC>[STATUS2]" then labDDEStatus is
updated with connected status information. This is only needed when
an application first starts, because once WinPack has some DDE
clients, labDDEStatus is automatically updated whenever the
connected state changes.

In the above, <ESC> means the character 1B hex.

Connected Status Information
----------------------------
This consists of a few lines of text.

Line 1: "<ESC>[STATUS]" or "<ESC>[STATUS2]" according to which item is
being used.

Line 2: "*** CONNECTED to a_callsign" e.g. "*** CONNECTED to G4IDE",
or "*** DISCONNECTED".

Line 3: "CTS=state".

Line 4: "DSR=state".

Line 5: "DCD=state".

Line 6: "DDE link count=number_of_current_DDE_links".

In the above, state can be "TRUE", "FALSE", "NULL" (DCD only), or,
if you are using BPQ or host mode, it is the first five characters
of the name of the mode in use, e.g. "BPQ" or "TF2.7".


Roger Barker, G4IDE
February 1997