I most certainly know the definition of catholic. I also know that local ordinaries have some flexibility.
A perfect example is Canada. In Canada, they use the Apostle’s Creed instead of the Nicene Creed.
While the General Instruction of the Roman Missal is the guiding document for the celebration of the Mass, there is some variance.
“While the General Instruction of the Roman Missal is the guiding document for the celebration of the Mass, there is some variance.”
And we all know how screwed up the GIRM has been, needing constant correction since Bugnini’s new Mass:
http://old.usccb.org/romanmissal/translating_sixquestions.shtml