Traditional adjustment fields are one type of adjustment field. At least 3 and ideally 5 adjustment fields are defined on the form definition.
Later, each time a filled-in form is scanned, FORMS checks each adjustment object’s size, position and shape. When three adjustment objects are found on the form that are identical to ones you defined on a form definition included in the job, the form is positively identified.
You do not have to add special adjustment characters to your forms; most forms already have objects suitable for the purpose. Even white objects on black backgrounds can be used as adjustment objects.
Defining a traditional adjustment field
How FORMS identifies forms that have traditional adjustment fields