When you select this button, you will see a list of all the fields for this particular procedure.
Among these fields you may have several fields that you don't want to be touched, like for example "quantity" fields, that shouldn't be changed by the template.
You simply select those fields in this list, and they are not going to be touched by DigitChanger in this particular procedure.
This option will be always activated. The value specified here will take effect in addition to the global All but these option.