Some of our proposals (Medical/Health, TechArticle, LRMI) and also some of our Yandex people have common ideas floating around.
I mean that currently a publisher cannot explicitly specify target audience of his site/page/CreativeWork.
Medical vocabulary proposal contains a type MedicalAudience, which splits people of medicine into categories expressed as an enumeration.
LRMI proposal contains intendedEndUserRole property with the same purpose, contaning some text (which is also a soft enum).
TechArticle proposal contains property named technicalAudience with Text type.
I think we should make a common skeleton for target audiences, so that every new proposal could build in a new specific audience into our schema.
First, I made a wiki proposal page, containing some common thoughts about describing target audience of a CreativeWork:
It can be applied to schema.org/WebPage and schema.org/Product class as well.
The key concept is that we cannot force all the sites to markup with constraints, but some of them may want to have some positive recommendations for expected target audience.
That's why we should provide a way for publishers to say, which people they want to visit their site (opposite to which they do *not* want).
Second, the proposal also contains some specific audience constrains:
1) age and gender for PeopleAudience
2) a more specific type ParentAudience (with properties about child age) for describing parents as target audience
Some examples can be found on the Wiki.
I think the earlier we structure audiences, the less work we'll need to change the schema in the future.
Would be glad to hear your thoughts.