How to stop tcl script after warning message?

Hi everybody,

 

how can I stop a tcl script, after a warning message?

I have the following expression:

 

 

if {$outerdiameter > $innerdiameter}  {
} else  {
   tk_messageBox -message 'WARNING - Please check your input! \n
  Outer diameter = $outerdiainput mm \n
  Inner diameter = $innerdiainput mm' -type ok

}

 

outer- and innerdiameter are variables I defined earlier in my script.

 

Now I would like to stop the tcl script from working on, if the message box appears.

Or even better would be if it is possible to add some command that after the message box appears tcl moves back to a specified line in the script. Something like go to line 5.

 

thanks in advance!