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AFW - Signature Problems

Problem: Beginning of Signature -> Sigdashes

Those who reply to messages with a signature have the problem to quickly remove the (quoted) signature from their reply. To make it easier to recognize signature a mark to signal the beginning of the signature was introduced: the signatures dashes line - known as "sigdashes" for short.

The sigdashes line enables programs to find the beginning of signatures and therefore be able to colorize them when viewing the messages - and to remove the automatically on replies.

see also: sigdashes page

Problem: End of Signature

The sigdashes line marks the beginning of a signature - but there is no special mark for the end of a signature.

A natural end for the signature is the end of the message, of course. However, messages can be "multi-part", so the signature might be the end of the first (plain text) part - but there be more to follow. If there is an text/plain attachment then the client might include it in the reply - and deletion after the sigdashes would delete the included plain text part, too. this would be a mistake, of course.

Another natural ending is an empty line. So many signature removal algorithms will delete the sigdashes unto the next empty line. Thefore you are advised to *exclude* empty lines from your signature; make your signature a *single* paragraphs. if you need an empty line for visibility then add a line with only a space in it.

Signature Removal

So how do programs recognize the signature?

Rule: The signature is the first paragraph of the message's body that starts with a sigdashes line. [A paragraph is a sequence of non-empty lines.]

NOTE for programmers of user agents: The user agent SHOULD make the signature visible for composition of the message, ie the user SHOULD see what he is appending to his message!

Assumption: It is assumed that the signature gets appended by the user agent with a proper sigdashes line and that the user does not include further sigdashes lines in his message before that line.

by the way - it is quite unlikely that people start a line with two dashes as a separator and also add a space after that. This makes it unlikely that someone might include such a line as part of his message.

Conflict with attachments: As there is the possibility for attached messages to a message we make the assumption that the actual message is always the first part of the whole message. Thus programs can look for the first occurrence of a sigdashes line. The signature can still contain further sigdashes lines without any problem.

Some attachments are simply "appended", though. This is often the case with post to binary groups which contain uuencoded or binhexed files.

However, most of these appended files come after an empty line, so it a good idea to separate these from signature by disallowing empty lines in signatures. Therefore a signature is the first paragraph which starts with a sigdashes line.

Consequence: The newsreader therefore MUST eliminate empty lines from the signature or add a space into them to make them non-empty to avoid problems with program which hide or remove signatures.


	Append signature?				no ->          exit
	Does sigfile exist?				no -> warning; exit
	Is sigfile readable?				no -> warning; exit
	Remove empty lines (delete or add space)
	/* Give warnings - optional */
	Does sigfile contain tabs?			yes -> warning
	Does sigfile contain 8bit chars?		yes -> warning
	Does sigfile contain lines with >80 chars?	yes -> warning
	Does sigfile contain lines with trailing whitespace?	yes -> warning
	Add to buffer:  sigdashes line
	Add to buffer:  first four lines of sigfile
To ensure that the signature is a single paragraph Of course it would be even nicer if signatures had the name and address in the first line, so you could scan them more easily. But such strict rules are enforced for headers already, so there is no need to enforce them on signatures. However, it is still a good idea to put name and a valid(!) address first.

Problem: Size

Signatures increase the size of messages - and bigger messages take more space, of course. Some clients did not check the size of signatures so they would simply add an arbitrary amount of data with every message - and send it away.

Often people not notice how much data they would send because the client does not add the signature to the data you are editing. instead, it will append the signature only before sending it away.

It always was lots of fun creating or adding to a sigfile when someone forgot to log out. They would then send a lot more data than they thought they were.. hehe

Anyway, there was much talk on how big a signature needs to be. People settled on the four line limit. And programmers added another feature to their clients: They would enforce the four-line limit by automatically cutting off the signature after the fourth line.

Sven Guckes <>
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