Adding NamingSystems: why and how?

[jd-nictiz]

On main we have 4 NamingSystems living in the terminology folder, added by this commit:
a7e942a

These are the only 4 NamingSystems we have at the moment, which raises questions:

• Why were they added? And why should or shouldn't we add others relating to other zibs?
• How are they added and maintained?

[ahenket]

A NamingSystem:
Defines a specific code system or identifier system, so that it can be noted in a registry for other systems to find and understand an identifier.

The data for any NamingSystem comes from decor.nictiz.nl by consulting any of the available OID registries. The OID registries are - for now - maintained by a single person (me) through automated conversion and sometimes a manual tweak.

Generically speaking it helps implementers to know what "2.16.840.1.113883.2.4.4.1.361" means when deemed relevant in a profile. You could do that through documentation inside the profile obviously as well. A NamingSystem could offer single point of reference for that.

I would only consider a NamingSystem when applying OIDs in FHIR. URIs are normally self-explanatory.

[jd-nictiz]

Some further analysis:

We use OIDs in ValueSet. and CodeSystem.identifier.value. Also serving these as NamingSystems would not provide much more information.

The cases where we use a fhir.nl URI defined at http://hl7.nl/wiki/index.php?title=OIDs_en_FHIR_System_URIs are perhaps the most useful, as these URIs do not lead to this wiki page