$ZA contains a status determined by the last read on the device. The value is a decimal integer with a meaning determined by the device as follows:

For Terminal I/O:

0: Indicating normal termination of a read operation

1: Indicating a parity error

2: Indicating the terminator sequence was malformed or too long

3: Indicating hardware contention or failure

4: Indicating a system configuration problem

5: Indicating a process limit was exceeded or the process does not have a required privilege

9: Indicating a default for all other errors

For Sequential Disk and Tape Files I/O:

0: Indicating normal termination of a read operation

9: Indicating a failure of a read operation

For Foreign Magnetic Tape I/O:

0: Indicating normal termination of an operation

1: Indicating End-Of-Tape (EOT) was encountered

9: Indicating a default for all other errors

For Mailbox I/O:

A decimal integerIndicating $JOB (VMS PID) of the process that wrote the last message the current process read

For socket:

0: Indicating normal termination or time out

9: Indicating failure of a read operation

$ZA refers to the status of the current device. Therefore, exercise care in sequencing USE commands and references to $ZA.