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Cream of the Crop 21 (Terry Blount) (October 1996).iso
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HEADERS.DOC
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Text File
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1993-04-27
|
21KB
|
413 lines
WARNING: This document is subject to change at any time. Any changes made
will be indicated by a vertical bar (|) in column 1 of the file.
| Last update: 04/27/93
=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=
The following is the standard message header (128 byte block) with only
slight modifications:
typedef struct {
char Status;
bassngl MsgNumber;
bassngl RefNumber;
char NumBlocks; <- see bit #7 of ExtendedStatus
char Date[8];
char Time[5];
char ToField[25];
bassngl ReplyDate;
char ReplyTime[5];
char ReplyStatus;
char FromField[25];
char SubjField[25];
char Password[12];
char ActiveFlag;
char EchoFlag;
char Reserved1[4]; <- reserved was 6 bytes
char ExtendedStatus; <- new byte - 0 for compatibility, accept 32 also
char Reserved2; <- last of original reserved bytes
} msgheadertype;
The message base format remains almost 100% identical to the PCBoard v14.x
standard. In fact, it remains 100% compatible having just one byte
different, which was not previously used by PCBoard.
The byte at offset 126 (i.e. the 127th byte of the 128 byte header) has a
new function. It is now used to indicate that extended header information
will be found in the body of the message.
The byte, referenced as ExtendedStatus above, will contain a 0 by default to
indicate that no extended header information is available. A value of 32
will also be accepted to indicate the same thing since some programs may be
placing a space instead of a null character in the reserved byte(s).
If ExtendedStatus is not equal to 0 or 32 then it is assumed that extended
header information is available, however, a follow-up check of the message
body will determine the true existence, or lack thereof, of such information.
For speed purposes, ExtendedStatus will be divided into 'bits' as follows:
bit 0 = extended header has TO information
bit 1 = extended header has FROM information
bit 2 = extended header has SUBJECT information
bit 3 = extended header has CARBON LIST TO information
bit 4 = extended header has ATTACHED FILE information
bit 5 = ignore - this bit is equal to decimal 32
bit 6 = extended header has either REQRR or ACKRR information
bit 7 = reserved for future use
Bit 6 indicates that either an REQRR (request return receipt) or an ACKRR
(acknowledge return receipt) extended header is in the message.
The following structure will be used within the contents of a message body
whenever an extended header is to be included:
typedef struct {
int Ident; 16639 (40FF hex)
| char Function[7]; TO,TO2,FROM,FROM2,SUBJECT,ATTACH,LIST,ROUTE,ORIGIN,REQRR,ACKRR,ACKNAME,PACKOUT
char Colon; always set to ":"
char Descript[60]; user name, subject, filename
char Status; NONE, READ (if LIST)
char CarReturn; 0xE3 or 0x0D
} msgextendtype;
There can be as many extended headers as desired. In fact, no headers at all
is possible even though the ExtendedStatus from the message header told
PCBoard to expect to find one. This, of course, has a negative impact on
efficiency (don't set the flag unless you really intend to put an extended
header in the body of the message) but maintains complete compatibility with
previous versions of PCBoard which totally ignored the values found where the
ExtendedStatus byte is now located.
The first field, Ident, serves to indicate that a truly valid header is about
to follow. Ident is an integer value of 40FFh. Stored in the file it is
seen as an ascii 255 character followed by an @ character.
Older software will not expect this extended header to be in there and will
display the header to the user. The format of the information, however, is
such that it will be meaningful, albeit, somewhat annoying to see.
| The function of the header is written in english. Right now the following
| are valid values for PCBoard: "TO ", "TO2 ", "FROM ", "FROM2 ",
| "SUBJECT", "ATTACH ", "LIST ", "ROUTE ", "ORIGIN ", "REQRR ", "ACKRR ",
| "ACKNAME" and "PACKOUT". Any other values are permissable but will be
| ignored by PCBoard v15.0 unless and until future updates to PCBoard add
| new-standards.
The next character in the header is a colon which is then followed by the
appropriate text for the header. For example, the header might be structured
like this:
<255><@>SUBJECT:any subject you wish to put here, up to 60 characters
Notice how an older program, which is not PCB v15.0-aware, will still display
something intelligible to the user who is reading the message. Because the
entire text is in english the user will be faced with extra information that
is not utilized by the software he is using, but at the same time, the extra
information does not make his software incompatible or unusable. This
protects the user's investment in software and time, especially if the author
is no longer supporting the program, or the user does not have time to switch
programs or upgrade to a newer package which may have more bells and whistles
than he cares to learn.
Of course, older packages will not be able to take advantage of the added
functionality since the header information will be very difficult to enter
properly via the keyboard. So, while remaining compatible with older
software, to take advantage of the new features a user will still have to
upgrade to a newer release of the package.
The text for the header may be up to 60 bytes long. If the Function is set
to "TO" then the header indicates a longer, or alternate, name should be used
when displaying the TO: field of the message. If the Function is set to
"LIST" then the header indicates the name of ONE of the users who is to
receive the message. There may be more than one "LIST" header, in fact, it
is expected that any time you create a carbon copy list you will be sending
the message to two or more users. If the Function is set to "FROM" then it
indicates a longer, or alternate, name should be displayed for the FROM:
field. If set to "SUBJECT" then a longer, or alternate, subject is
displayed. If set to "ATTACH" then the description field indicates the name
of the attached file. If set to ROUTE then message routing information (for
netmail transfers) will be included. If set to ORIGIN then the origin of the
message (for netmail transfers) will be included. If set to REQRR then
PCBoard will generate a Return Receipt when the user reads the message
online. Mail Doors will need to be enhanced to perform the same
functionaility. If set to ACKRR this will indicate that an acknowledgement
to the Return Receipt is contained in the message. One additional header,
the ACKNAME, will be included with ACKRR to complete the acknowledgement.
The next byte is the extended header status byte. To help guarantee that the
header is valid, there are only three possible values for this field. They
are: 'N', and 'R'. These values are used as follows:
'N' indicates that there is no status - it is used just for verification
'R' indicates that a user in a CARBON COPY LIST has read the message
The 'R' allows PCBPack to determine when all intended recepients have read
the message. Each user is listed in a separate header and each user
therefore has a separate status byte to indicate when it has been read. Once
all users have read the message it may then be deleted.
Finally, the CarReturn byte is set to E3 hex. This is the same character
that is normally used by PCBoard to indicate the end of a line. By
terminating the header in this manner all non-v15.0-aware packages will be
able to properly display the entire header in a legible form. The 0D hex
value is used by foreign systems (such as the Chinese version of PCBo