Both the HRex Organization and Practitioner profiles requires the use of NPI IDs but they seem to have implemented it differently.

In the Practitioner profile, identifier.system is fixed to the value "http://hl7.org/fhir/sid/us-npi"

But in the Organization profile, the NPI slice of.identifier seems to use "http://terminology.hl7.org/CodeSystem/v2-0203","code":"PRN"" but doesn't fix the value

Is there a reason why Organization does do the same thing as practitioner?