WHEN EXCEPTION USE and HANDLER
Exception handling process can be described as an internal procedure so that more than one when-block has an identical exception-handler in common.
An exception handler described as an internal procedure is called a detached handler.
A detached handler begins with a HANDLER line and ends with an END-HANDLER line.
A HANDLER line holds a name of the handler. The rule for naming a handler is same as that of a numerical variable.
When you use a detached handler, replace WHEN EXCEPTION IN ～ USE ～ END WHEN with WHEN EXCEPTION USE ～ END WHEN. A WHEN-EXCEPTION-USE line holds the name of the detached handler.
100 WHEN EXCEPTION USE h 110 PRINT 1/A 120 END WHEN 130 WHEN EXCEPTION USE h 140 PRINT SQR(-1) 150 END WHEN 160 HANDLER h 170 PRINT EXTYPE 180 END HANDLER 190 END