Rice Lake Datamax M-Class - Manual (Page 44)

36 M-Class
The second label printed is the Test Label. This label is used to test the condition of the printhead, as shown below:
Good Print Quality Label:
Even pattern consistency
indicates correct printhead
operation.
Faulty Print Quality Label:
Streaks indicate a dirty or
faulty printhead. See Section
6.1 for cleaning instructions.