Undo Is Z Because Cut-and-Paste Pioneer Larry Tesler Picked It for the Apple Lisa, and Its Zigzag Reads as Do, Undo, Redo

In an email Brad Myers quoted in his 2016 Carnegie Mellon lecture slides, Larry Tesler says he chose X, C, V and Z for cut, copy, paste and undo on the Lisa himself, and that Z's three strokes stand for step forward, step back, step forward again.

By Chris Pirillo · October 31, 2026 · 5 min read

Chris, stitched from zigzag sewing trim, steps back along a zigzag ribbon path laid across an oversized beige keyboard — Illustration: LockerGnome

“The Lisa was the first system to assign XCVZ to cut, copy, paste and undo (shifted with the “apple” key). I chose them myself,” Tesler wrote, in the email as it appears on Myers’s slide.

Three of the four letters had reasons that were already lying around. “X was a standard symbol of deletion. C was the first letter of Copy. V was an upside down caret and apparently meant Insert in at least one earlier editor,” he wrote.

Z was the new one. It sat next to X, C and V on a U.S. QWERTY keyboard, “But its shape also symbolized the “Do-Undo-Redo” triad: top rightward stroke = step forward; middle leftward stroke = step back; bottom rightward stroke = step forward again.”

Trace a Z with your finger and you can see it. Tesler also made a narrower claim than “I invented the Undo shortcut”: “So X, C and even V were not novel. But I know of no use of Z to mean Undo before the Lisa.”

Undo itself was older than the Lisa, and Tesler never said otherwise. In his 2012 history in ACM Interactions, he says a PARC colleague told him about a command that Warren Teitelman “had introduced in his user-friendly LISP shell. It was aptly named undo. And it became our model.” At PARC, he and Tim Mott “had used dedicated keys for cut, copy, paste, and undo” in Gypsy, their 1974-75 editor.

The Lisa is where those dedicated keys became letters under one hand. Tesler went to Apple to work on the Lisa user interface and applications, and in the email he describes how its Undo behaved: “When Z undid only the most recent command, another Z redid it.” One Z took a step back; the next stepped forward again, just like the letter.

Why it matters

It settles a credit people still get wrong. Myers’s next slide notes that a 2009 New York Times column, quoted by Wikipedia, said the shortcut was picked by programmers at Xerox PARC. “Larry Tesler says that is incorrect,” the slide reads. Wikipedia’s Undo article still credits PARC programmers.

The keys sit where your left hand already is. Tesler picked Z partly because it “was next to X, C and V,” so the four editing commands you use most sit side by side on the bottom row.

Undo is what made modeless editing safe. Tesler’s whole project was removing modes, so you select something and then act on it. If you chose the wrong verb, his 2012 piece says, “she could invoke an operation that undid the command.” Without a cheap Undo, every click is a commitment.

Steal this

Use Ctrl-Y or Ctrl-Shift-Z when you undo one step too far. Tesler’s email names Ctrl-Y as Redo in Microsoft Office, and Myers’s slide lists Ctrl-Shift-Z in some other systems, so try both before you retype anything. This is like trying the other door handle before you call a locksmith.
Undo before you scramble. Pasted over the wrong thing or deleted a paragraph? Press Ctrl-Z (Cmd-Z on a Mac) before you do anything else, since in programs like Photoshop, Myers’s slides note, a new action erases the redo list. Kind of like backing up the car before you try a new route.
Give your own app’s shortcuts a reason a user can see. If you ship keyboard shortcuts, pick letters for their meaning or shape and keep the frequent ones together, the way Tesler did. It’s like labeling the light switches by the room instead of numbering them.

The slide doesn’t give the whole email. Myers quotes it with a gap, marked by an ellipsis, right before Tesler gets to Gypsy. Whatever sat in that gap, and whether anyone at PARC had pressed a letter key for Undo before the Lisa, is still Tesler’s word against a 2009 newspaper column.

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Undo Is Z Because Cut-and-Paste Pioneer Larry Tesler Picked It for the Apple Lisa, and Its Zigzag Reads as Do, Undo, Redo

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