From the arrangement of letters on the keyboard of a Linotype machine—typesetters would mark errors by running their fingers across the keys, and the results would sometimes accidentally find their way into print.
etaoin shrdlu (plural etaoin shrdlus)
- Nonsense, filler text, or an example of accidental typing.
1989, Alex Brown, In print: text and type, pages 137:
- You can see why compositors reflexively filled lines to be corrected with etaoin shrdlus.