Pay Type Set-up, cannot use "Blank" Shift Differential Method

Pay Type set-up:  In the documentation, the Shift Differential Method includes "blank" as a valid value, with the following description:

Blank: The system follows the shift differential method that is associated with the pay type from the
Payroll Transaction Constants table (F059116).

We would like to test this functionality, but the CMTH field defaults to a value of "1", and will not accept blank.  Would we need to update the data dictionary for CMTH and change the default value to "No Default Value"?  Is blank still a valid value for CMTH, or was this removed, and the documentation out of date?