This returns a string that represents the exception. Users should feel free to modify the format in subclasses.
This method sets an array that is passed by reference to the execution stack at the time of the exception. The top unsubscripted value is the number of execution levels.
array(n) is a string that indicates how the next level was created. It is empty for the current level. The value may be:
DO - issued a DO command
$$ - called an extrinsic function
XECUTE - issued an XECUTE command
BREAK - entered a debug prompt because of a <BREAK>
ERROR - entered a debug prompt because of an error
$ETRAP - executed a $ETRAP
CALLIN - entered via a callin
array(n,"PLACE") is the location of the last command executed at this level. It is a line reference followed by the command number on that line.