Etaoin shrdlu (/ˈɛtiɔɪn ˈʃɜːrdluː/,[1] /ˈeɪtɑːn ʃrədˈluː/)[2] is a nonsense phrase that sometimes appeared by accident in print in the days of "hot type" publishing, resulting from a custom of type-casting machine operators filling out and discarding lines of type when an error was made.
It appeared often enough to become part of newspaper lore – a documentary about the last issue of The New York Times composed using hot metal (July 2, 1978) was titled Farewell, Etaoin Shrdlu.
[4] The letters on type-casting machine keyboards (such as Linotype and Intertype) were arranged by descending letter frequency to speed up the mechanical operation of the machine, so lower-case e-t-a-o-i-n and s-h-r-d-l-u were the first two columns on the left side of the keyboard.
However, manipulating the matrices by hand within the partially assembled line was time-consuming and presented the chance of disturbing important adjustments.
To make the line long enough to proceed through the machine, operators would finish it by running a finger down the first columns of the keyboard, which created a pattern that could be easily noticed by proofreaders.