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Perhaps the simplest statement is "exit". It terminates the execution of a program at the point it is encountered. This statement is used to halt execution at a point other than the normal end of a program. It is not necessary to put "exit" at the end of a program.


The "exit" statement can also return a code to DOS. The low byte of the value (0-255) of an optional expression following "exit" is returned to DOS interrupt $21 function $4C. This return code can be tested in a batch file with an IF ERRORLEVEL statement. For example, the batch file used to run the compiler (XN.BAT) uses this feature to skip the assembly and link steps if there is an compile error. By convention, a returned value of 0 indicates no errors.