A signature block (often abbreviated as signature, sig block, sig file, .sig, dot sig, siggy, or just sig) is a block of text automatically appended at the bottom of an email message, Usenet article, or forum post.
An email signature is a block of text appended to the end of an email message often containing the sender's name, address, phone number, disclaimer or other contact information.
"Traditional" internet cultural .sig practices assume the use of monospaced ASCII text because they pre-date MIME and the use of HTML in email. In this tradition, it is common practice for a signature block to consist of one or more lines containing some brief information on the author of the message such as phone number and email address, URLs for sites owned or favoured by the author—but also often a quotation (occasionally automatically generated by such tools as fortune), or an ASCII art picture. Among some groups of people it has been common to include self-classification codes.
\_/ **************************** (\_/) / @ @ \ * "Purrrfectly pleasant" * (='.'=) ( > º < ) * Poppy Prinz * (")_(") `>>x<<´ * (firstname.lastname@example.org) * / O \ ****************************
Most email clients, including Mozilla Thunderbird, the built-in mail tool of the web browser Opera, Microsoft Outlook and Outlook Express, and Eudora, can be configured to automatically append an email signature with each new message. A shortened form of a signature block (sometimes called a "signature line"), only including one's name, often with some distinguishing prefix, can be used to simply indicate the end of a post or response. Most email servers can be configured to append email signatures to all outgoing mail as well.
Signature blocks are also used in the Usenet discussion system.
...orist it's an unnecessary optimization and a (to use your words) "performance hack", but I'm interested in a Real operating system --- not a research toy. =-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-= Theodore Ts'o bloom-beacon!mit-athena!tytso 308 High St., Medford, MA 02155 ty...@athena.mit.edu Everybody's playing the game, but nobody's rules are the same!
The Usenet standard RFC 3676 specifies that a signature block should be displayed as plain text in a fixed-width font (no HTML, images, or other rich text), and should be delimited from the body of the message by a single line consisting of exactly two hyphens, followed by a space, followed by the end of line (i.e., in C-notation:
"-- \n"). This latter prescription, which goes by many names, including "sig dashes", "signature cut line", "sig-marker", "sig separator" and "signature delimiter", allows software to automatically mark or remove the sig block as the receiver desires.
-- Brad Templeton, publisher, ClariNet Communications Corp. in...@clari.net The net's #1 E-Newspaper (1,160,000 paid sbscrbrs.) http://www.clari.net/brad/
Businesses do often automatically append signatures blocks to messages—or have policies mandating a certain style. Generally they resemble standard business cards in their content—and often in their presentation—with company logos and sometimes even the exact appearance of a business card. In some cases a vCard is automatically attached.
In addition to these standard items, email disclaimers of various sorts are often automatically appended. These are typically couched in legal jargon, but it is unclear what weight they have in law, and they are routinely lampooned.
Business emails may also be some signature block elements mandated by local laws:
While criticized by some as overly bureaucratic, these regulations only extend existing laws for paper business correspondence to email.
On web forums, the rules are often less strict on how a signature block is formatted, as Web browsers typically are not operated within the same constraints as text interface applications. Users will typically define their signature as part of their profile. Depending on the board's capabilities, signatures may range from a simple line or two of text to an elaborately-constructed HTML piece. Images are often allowed as well, including dynamically updated images usually hosted remotely and modified by a server-side script. In some cases avatars or hackergotchis take over some of the role of signatures.
With FidoNet, echomail and netmail software would often add an origin line at the end of a message. This would indicate the FidoNet address and name of the originating system (not the user). The user posting the message would generally not have any control over the origin line. However, single-line taglines, added under user control, would often contain a humorous or witty saying. Multi-line user signature blocks were rare.