I did not know, but I know where to look!

"Before there were computers, "etoain shrdlu" would occasionally appear in newspapers (especially in early sports news editions). It happened whenever a linotype operator realized that he had made a typographical error. It was the nature of those machines that a line started had to be finished in order to flush pieces of type already on the way to be set. Due to the way the machine was designed, "etoain shrdlu" was the most efficient phrase possible for this purpose. Most of the time, the frame of type for the page would be manually fixed. For some early editions, there was no time to fix the problem, resulting in "etoain shrdlu" being published."

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