sig block
sig block: /sig blok/ [UNIX; often written `.sig' there] n.
Short for `signature', used specifically to refer to the
electronic signature block that most UNIX mail- and news-posting
software will automagically append to outgoing mail and news.
The composition of one's sig can be quite an art form, including an
ASCII logo or one's choice of witty sayings (see sig quote,
fool file, the); but many consider large sigs a waste of
bandwidth, and it has been observed that the size of one's sig
block is usually inversely proportional to one's longevity and
level of prestige on the net. See also doubled sig.