GetLink returns a Link{id,href} object for the given url/id (or just url if id is empty).

GetLinkWithID returns a Link{id,href} object for the given url/id (or just url if id is empty).

CodelistURL set by main() to make accessible to all models users.

Element is a item in a list within a Response.

Link is a combination of ID and HRef for the object in question.

Response models a node in the hierarchy.