Identifier

A technical identifier - identifies some entity uniquely and unambiguously.

= Must Support, = Is Modifier, = QiCore defined extension

Field	Card.	Type	Description
use	0..1	String	The purpose of this identifier.
type	0..1	Concept	A coded type for the identifier that can be used to determine which identifier to use for a specific purpose.
system	0..1	String	Establishes the namespace for the value - that is, a URL that describes a set values that are unique.
value	0..1	String	The portion of the identifier typically relevant to the user and which is unique within the context of the system.
period	0..1	Interval<DateTime>	Time period during which identifier is/was valid for use.
assigner	0..1	Organization	Organization that issued/manages the identifier.