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Condition-Handling Routines and Services 9.9 Types of Condition Handlers 9.9.2 Interaction Between Default and User-Supplied Handlers Several results are possible after a routine signals, depending on a number of factors, such as the severity of the error, the method of generating the signal, and the action of the condition handlers you have defined and the default handlers. Given the severity of the condition and the method of signaling, Figure 9–12 lists all combinations of interaction between user condition handlers and default condition handlers. Figure 9–12 Interaction Between Handlers and Default Handlers Severity of Condition User Handler Specifies CONTINUE User Handler Specifies UNWIND Default Handler Gets Control No Handler Found (Bad Stack) Exception Condition Is Signaled by a Call to LIB$SIGNAL or Detected by Hardware WARNING, INFO, or ERROR SEVERE RETURN RETURN UNWIND UNWIND Issue Condition Message Call Last− Chance Handler RETURN EXIT Issue Condition Message Call Last− Chance Handler EXIT EXIT Exception Condition Is Signaled by a Call to LIB$STOP LIB$STOP Forces Severity to SEVERE Message: "Attempt to continue from stop" EXIT UNWIND Issue Condition Message Call Last− Chance Handler EXIT EXIT ZK−4257−GE 9–44 Condition-Handling Routines and Services
