UTSL: // [UNIX] n. On-line acronym for `Use the Source,

:UTSL: // [UNIX] n. On-line acronym for `Use the Source, Luke' (a
pun on Obi-Wan Kenobi's "Use the Force, Luke!" in "Star
Wars") --- analogous to {RTFS} (sense 1), but more polite. This
is a common way of suggesting that someone would be better off
reading the source code that supports whatever feature is causing
confusion, rather than making yet another futile pass through the
manuals, or broadcasting questions on USENET that haven't attracted
{wizard}s to answer them.

Once upon a time in {Elder Days}, everyone running UNIX had
source. After 1978, AT&T's policy tightened up, so this objurgation
was in theory appropriately directed only at associates of some
outfit with a UNIX source license. In practice, bootlegs of UNIX
source code (made precisely for reference purposes) were so
ubiquitous that one could utter it at almost anyone on the network
without concern.

Nowadays, free UNIX clones are becoming common enough that almost
anyone can read source legally. The most widely distributed is
probably Linux, with 386BSD (aka {jolix}) running second. Cheap
commercial UNIXes with source such as BSD/386 are accelerating this
trend.
-- The AI Hackers Dictionary