Use the ATTN statement to define a routine that TSO/E executes when the user causes an attention interrupt. The attention interrupt halts execution of a CLIST so that the user can terminate or alter its processing.

                     .-OFF----.   
>>-+--------+--ATTN--+-action-+--------------------------------><
   '-label:-'                     

label

A name the CLIST can reference in a GOTO statement to branch to this ATTN statement. label is one-to-31 alphanumeric characters, beginning with an alphabetic character.

OFF

Any previous attention action is nullified. Do not use ATTN OFF within an attention routine.

action

specifies either:

1. One TSO/E command, commonly an EXEC command that invokes an attention processing CLIST, or a null (blank) line. An attention processing CLIST can execute multiple TSO/E commands, while the action can execute only one.
2. A DO-END sequence constituting an attention exit routine. This routine can contain CLIST statements, including the RETURN statement or EXIT statement, and one TSO/E command, or a null line.

If a null line is executed, TSO/E ignores the attention and execution continues at the point where the interruption occurred.

If an EXIT statement is executed, the attention is ignored and the CLIST is terminated.

If a TSO/E command is executed, control is given to the command.

When a TSO/E command, an EXIT statement, or a null line is executed, TSO/E ignores all other.

If the attention routine does anything other than terminate the CLIST, use the MAIN operand of the CONTROL statement to protect the CLIST from being flushed from the input stack when an attention interrupt occurs. For more information, see CONTROL statement.