Brother DCP6690CW Service Manual page 247

(22) A head/carriage unit is assigned a property code that represents the properties unique to
that head/carriage unit. The property code is printed on head property labels--bar code label
and QR code label, each of which is attached to the lower cover and carriage-head flat
cable, respectively.
When you remove the head/carriage unit and store it separately from the machine, remove
the property label (bar code label) from the lower cover and store it together with the head/
carriage unit.
If you replace the head/carriage unit, attach the property label (bar code label) that comes
with the new head/carriage unit to the lower cover as shown below.
Lower cover
Head property label (Bar code)
Property code
(16-digit)
LT cover
Carriage-head flat cable
Head property label (QR code)
Head/carriage unit
(6_58)
6-66
Confidential