The default/suggested phrasing to use when prompting a human to capture the data element in question form (e.g. In a survey).

Question and label serve similar purposes in they both can be used to prompt for capturing a data element. Whether the question form or label form should be used will depend on the type of instrument being used to capture the information. The ordering is in order of preference. I.e. Most preferred question form is listed first. Note that this is for alternate phrasings of the question. Language translations are handled using the ISO 21090 string translation extensions.

unique id for the element within a resource (for internal references).

An Extension

Source of the definition for the extension code - a logical name or a URL.

The definition may point directly to a computable or human-readable definition of the extensibility codes, or it may be a logical URI as declared in some other specification. The definition should be version specific. This will ideally be the URI for the Resource Profile defining the extension, with the code for the extension after a #.

Value of extension - may be a resource or one of a constrained set of the data types (see Extensibility in the spec for list).