V.E.R.A. -- Virtual Entity of Relevant Acronyms (February 2016):

TLA
       Three Letter Acronym (slang)


The Jargon File (version 4.4.7, 29 Dec 2003):

TLA
 /T?L?A/, n.

    [Three-Letter Acronym]

    1. Self-describing abbreviation for a species with which computing
    terminology is infested.

    2. Any confusing acronym. Examples include MCA, FTP, SNA, CPU, MMU, SCCS,
    DMU, FPU, NNTP, TLA. People who like this looser usage argue that not all
    TLAs have three letters, just as not all four-letter words have four
    letters. One also hears of ?ETLA? (Extended Three-Letter Acronym,
    pronounced /ee tee el ay/) being used to describe four-letter acronyms; the
    terms ?SFLA? (Stupid Four-Letter Acronym), ?LFLA? (Longer Four Letter
    Acronym), and VLFLA (Very Long Five Letter Acronym) have also been
    reported. See also YABA.

    The self-effacing phrase ?TDM TLA? (Too Damn Many...) is often used to
    bemoan the plethora of TLAs in use. In 1989, a random of the journalistic
    persuasion asked hacker Paul Boutin ?What do you think will be the biggest
    problem in computing in the 90s?? Paul's straight-faced response: ?There
    are only 17,000 three-letter acronyms.? (To be exact, there are 26^3 =
    17,576.) There is probably some karmic justice in the fact that Paul Boutin
    subsequently became a journalist.


The Free On-line Dictionary of Computing (30 December 2018):

three-letter acronym
TLA

    (TLA) The canonical, self-describing acronym for the
   name of a species with which computing terminology is infested.
   Examples include MCA, FTP, SNA, CPU, MMU, DMU, FPU,
   TLA.

   This dictionary contains many TLAs.

   Sometimes used by extension for any confusing acronym.  People
   who like this looser usage argue that not all TLAs have three
   letters, just as not all four-letter words have four letters.
   One also hears of "ETLA" (Extended Three-Letter Acronym) being
   used to describe four-letter acronyms.  The term "SFLA"
   (Stupid Four-Letter Acronym) has also been reported.

   See also YABA.

   The self-effacing phrase "TDM TLA" (Too Damn Many...) is used to
   bemoan the plethora of TLAs in use.  In 1989, a random of the
   journalistic persuasion asked hacker Paul Boutin "What do you
   think will be the biggest problem in computing in the 90s?"
   Paul's straight-faced response: "There are only 17,000
   three-letter acronyms." (To be exact, there are 26^3 = 17,576.)

   (2014-08-14)