Tyco 1540 - Manual (Page 22)

Use the key to set the fourth digit to the required value.
Press the >> key to confirm your selection. If the unit accepts
your entry, the Confirmation screen will appear.
If the unit does not accept your entry, e.g. an incorrect
password, a rejection screen will appear, with dashes on the
bottom line.
The Confirmation screen shows the entered number on the
bottom row with all decimal points showing.
If the displayed number is correct, press the >> key to move to
the next Set-up screen.
If not, press the key to return to restart the number entry.
The first digit entry screen will appear.
If a rejection screen appears, press the key to restart the
entry procedure.
20 Integra 1540, 1000, 0640, 0440, 0340, 0240 Issue 1 04/03
Confirmation
Rejection
Fourth digit