Y14.43-2011 Dimensioning and Tolerancing Principles for gages and fixtures
6.2.6.1 and 6.2.6.2 has similar wording for Datum Target tolerance dimensions that state use 10% or less of largest tolerances for form, orientation, and location. This also discusses "company having internal process standard or other general or local tolerances to provide the applicable tolerances to basic dimensions"
I interpret this as tolerance is derived from what you are working with, a high precision machine shop with location Tolerancing of .002" and a casting house with Tolerancing to .040" do not have the same gage fixture Tolerancing but need to create those based on the manufacturing realities that are being met.
