short form of the name, "tape archive," the command to create a tarball. also a tcllib module for reading and writing tarballs. more to come here soon
There's code to decode and unpack a tar file in the SDX starkit utility, unwrap and look at lib/app-sdx/tgz2kit.tcl, it's about 25 lines. - jcw
the sdx untar does not respect file permissions and owners, nor special files.
DKF: Tar is also, and coincidentally, a black sticky substance that traps stuff that falls into it (e.g. the La Brea Tar Pits in LA). In computing, this brings on the term "a tar-pit project", which sucks in all effort that goes even close and swallows it all without trace. Avoid tar pits by using Tcl/Tk!
LV I've tended to refer to this type of effort as a black hole. I've also heard it referred to as a tar baby (which refers back to old children's tales of Brer Rabbit and company [L1 ].
ECS: The first reference I know to "a tar-pit project" is from Fred Brooks' The Mythical Man-Month: Essays on Software Engineering [L2 ] and [L3 ].