SIG

subdivision of a computer user's group that meets to discuss a very specific issue

Sig may refer to:Sig (rune), an Armanen runeSig (Jak and Daxter), a character from the Jak and Daxter video game seriesSignificant figures (known as sig figs or sig digs), an expression of measurement precisionSignature block (known as sig block or sig file), an appendix to an e-mail, Web forum post, or Usenet messageSIGARMS, a gun manufacturer.Sigurd "Sig" Hansen, captain of the F/V Northwestern
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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 e-mail message, Usenet article, or forum post. This has the effect of "signing off" the message. 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. Note that a sig block is not the same as a digital signature. A sig block is easily forged, whereas a digital signature uses cryptographic techniques to provide verifiable proof of authorship.
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mr, Mister, title of respect for a man that is prefixed to his name

abbr. of following

adj. shallow, shoaly, fordable

v. squeeze