Halt Script
Forces all scripts (including any sub-scripts or external scripts) to stop immediately.
Halt Script
This script step is also supported in web publishing and in a FileMaker Server scheduled script.
Originated in 
FileMaker Pro 6.0 or earlier
While pressing Esc will also halt a script, Halt Script is useful if you are also using the Allow User Abort script step to disable the Esc key. Halt Script stops the script when Allow User Abort is set to Off.
You can use the Halt Script script step with the Show Custom Dialog script step to present a user with options. If the user clicks Cancel, the script stops; otherwise, the script continues.
Show Custom Dialog ["Delete all records?"]
If [Get (LastMessageChoice) = 2]
Halt Script
End If
Delete All Records [No Dialog]
Related topics 
Script steps reference (alphabetical list)
Script steps reference (category list)