Vector Basic Interpreter Basic 80 Reference Manual - page 80
Extended, Disk
To enable error trapping and specify
the
first
line of the error handling subroutine.
Once error trapping has been enabled all
errors
detected,
including
direct
mode errors
(e.g.,
Syntax
errors),
will
cause
a
jump
to
the
specified
error
handling subroutine.
If number> does not exist, an ·Undefined line" error results. To disable error trapping, execute an ON EUOR GOTO o. Subsequent errors will print an error message and halt execution. An ON ERROR GOTO 0 statement that appears in an error trapping subroutine causes BASIC-SO to stop.and print the error message for the error that caused the trap. It is recommended that all error trapping subroutines execute an ON ERROR GOTO 0 if an error is encountered for which there is no recovery action. If an error occurs during execution of an error handling subroutine, the BASIC error message is printed and execution terminates. Error trapping does not occur within the error handling subroutine. 10 ON ERROR GOTO 1000