$Canceled
is a symbol returned when notebook input is canceled, for example from a dialog box.
Examples
Basic Examples (1)
Display a dialog window with a cancel button:
When the button is clicked, the value $Canceled is returned as the value of the DialogInput:
Wolfram Research (2007), $Canceled, Wolfram Language function, https://reference.wolfram.com/language/ref/$Canceled.html.
Text
Wolfram Research (2007), $Canceled, Wolfram Language function, https://reference.wolfram.com/language/ref/$Canceled.html.
CMS
Wolfram Language. 2007. "$Canceled." Wolfram Language & System Documentation Center. Wolfram Research. https://reference.wolfram.com/language/ref/$Canceled.html.
APA
Wolfram Language. (2007). $Canceled. Wolfram Language & System Documentation Center. Retrieved from https://reference.wolfram.com/language/ref/$Canceled.html