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.)