AT&T 6300 Programmer's Manual page 57

Getting Started
For example, running a program which
contains:
100 FOR K=
will cause:
Missing operand in 100
OK
If an error occurs and the error trapping is
enabled (programmed interrupt), program
execution is transferred to the line specified by
the ON ERROR statement.
An error trapping routine should check for all
the particular errors that the user wishes to
recover from, and should specify the course of
action to be taken in each case.
This involves either correcting the error, and
resuming execution at a specified statement
or; returning to Command Level.
Example
10 ON ERROR GOTO 100
20 INPUT "WHAT IS YOUR BET";B
30 IF B>5000 THEN ERROR 200
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