"A word, letter, number, or other symbol used in a code system to mark, represent, or identify something." - Dictionary.com. This data type represents a "coded element" - some label made up of a series of letters or numbers which can be referenced in a code system or value set. A code must be unique within a given coding system, but may not be unique across coding systems. For example, "AU" might mean "Gold" in a chemistry coding system, while it might mean "Australia" in a country coding system. This is why this coded element class contains both the code and the coding system in which it is defined (one can think of a coding system as a namespace in some respects).
Each target standard (which we are treating as "platforms" in a model-driven architecture sense) represents coded concepts differently. Some standards, like HL7 v2 have multiple "flavors" of coded concepts. When generating artifacts based on a particular standard, this data type will be substituted with a specific structure particular to the target standard.
Note that HL7 FHIR contains an additional element, "primary", which is not in the FHIM. Primary is used to signify which code in a collection of codes is the one that was chosen by the user (as opposed to translations of that code).
"A Coding is a representation of a defined concept using a symbol from a defined code system" HL7 FHIR, Coding

Attributes
String	code	This property is a unique identifier of or label for an entry in a coding system. Note that this property will be replaced by some other concept or group of concepts when this abstract class is replaced by a specific class for a given target platform. "A symbol in syntax defined by the system. The symbol may be a predefined code or an expression in a syntax defined by the coding system (e.g. post-coordination)." - HL7 FHIR, Coding.code.
CodeSystem	codeSystem	Pointer to "The identification of the code system that defines the meaning of the symbol in the code." - HL7 FHIR, Coding.system
String	displayText	This property contains the "display text" or "designation", which is the human-readable string representing the concept. Note that this property will be replaced by some other concept or group of concepts when this abstract class is replaced by a specific class for a given target platform. "A representation of the meaning of the code in the system, following the rules of the system." - HL7 FHIR, Coding.display.
NullFlavor	nullFlavor	This property indicates why the value property is empty. It uses the NullFlavor enumeration. This property must be valued when the value property is empty, and must be empty when the value property is valued.
String	originalText	"The text as seen and/or selected by the user who entered the data which represents the intended meaning of the user." - HL7 V3
Boolean	userSelected	"Indicates that this coding was chosen by a user directly - e.g. off a pick list of available items (codes or displays)." - HL7 FHIR, Coding.userSelected

 code

Public String code

This property is a unique identifier of or label for an entry in a coding system.
Note that this property will be replaced by some other concept or group of concepts when this abstract class is replaced by a specific class for a given target platform.
"A symbol in syntax defined by the system. The symbol may be a predefined code or an expression in a syntax defined by the coding system (e.g. post-coordination)." - HL7 FHIR, Coding.code.

Constraints:

Properties:

Aggregation	None
Alias
Association
Association End
Class	«CS» Code
Datatype
Default
Default Value
Is Composite	false
Is Derived	false
Is Derived Union	false
Is Leaf	false
Is Ordered	false
Is Read Only	false
Is Static	false
Is Unique	true
Keywords
Lower	0
Lower Value	(0)
Multiplicity	0..1
Name	code
Name Expression
Namespace	«CS» Code
Opposite
Owner	«CS» Code
Owning Association
Owning Template Parameter
Qualified Name	FHIM::Datatypes::Code::code
Stereotype
Template Parameter
Type	String
Upper	1
Upper Value	(1)
Visibility	Public

 codeSystem

Public CodeSystem codeSystem

Pointer to "The identification of the code system that defines the meaning of the symbol in the code." - HL7 FHIR, Coding.system

Constraints:

Properties:

Aggregation	None
Alias
Association	code_codeSystem
Association End
Class	«CS» Code
Datatype
Default
Default Value
Is Composite	false
Is Derived	false
Is Derived Union	false
Is Leaf	false
Is Ordered	false
Is Read Only	false
Is Static	false
Is Unique	true
Keywords
Lower	1
Lower Value	(1)
Multiplicity	1
Name	codeSystem
Name Expression
Namespace	«CS» Code
Opposite
Owner	«CS» Code
Owning Association
Owning Template Parameter
Qualified Name	FHIM::Datatypes::Code::codeSystem
Stereotype
Template Parameter
Type	CodeSystem
Upper	1
Upper Value	(1)
Visibility	Public

 displayText

Public String displayText

This property contains the "display text" or "designation", which is the human-readable string representing the concept.
Note that this property will be replaced by some other concept or group of concepts when this abstract class is replaced by a specific class for a given target platform.
"A representation of the meaning of the code in the system, following the rules of the system." - HL7 FHIR, Coding.display.

Constraints:

Properties:

Aggregation	None
Alias
Association
Association End
Class	«CS» Code
Datatype
Default
Default Value
Is Composite	false
Is Derived	false
Is Derived Union	false
Is Leaf	false
Is Ordered	false
Is Read Only	false
Is Static	false
Is Unique	true
Keywords
Lower	0
Lower Value	(0)
Multiplicity	0..1
Name	displayText
Name Expression
Namespace	«CS» Code
Opposite
Owner	«CS» Code
Owning Association
Owning Template Parameter
Qualified Name	FHIM::Datatypes::Code::displayText
Stereotype
Template Parameter
Type	String
Upper	1
Upper Value	(1)
Visibility	Public

 nullFlavor

Public NullFlavor nullFlavor

This property indicates why the value property is empty. It uses the NullFlavor enumeration. This property must be valued when the value property is empty, and must be empty when the value property is valued.

Constraints:

Properties:

Aggregation	None
Alias
Association
Association End
Class	«CS» Code
Datatype
Default
Default Value
Is Composite	false
Is Derived	false
Is Derived Union	false
Is Leaf	false
Is Ordered	false
Is Read Only	false
Is Static	false
Is Unique	true
Keywords
Lower	0
Lower Value	(0)
Multiplicity	0..1
Name	nullFlavor
Name Expression
Namespace	«CS» Code
Opposite
Owner	«CS» Code
Owning Association
Owning Template Parameter
Qualified Name	FHIM::Datatypes::Code::nullFlavor
Stereotype
Template Parameter
Type	NullFlavor
Upper	1
Upper Value	(1)
Visibility	Public

 originalText

Public String originalText

"The text as seen and/or selected by the user who entered the data which represents the intended meaning of the user." - HL7 V3

Constraints:

Properties:

Aggregation	None
Alias
Association
Association End
Class	«CS» Code
Datatype
Default
Default Value
Is Composite	false
Is Derived	false
Is Derived Union	false
Is Leaf	false
Is Ordered	false
Is Read Only	false
Is Static	false
Is Unique	true
Keywords
Lower	0
Lower Value	(0)
Multiplicity	0..1
Name	originalText
Name Expression
Namespace	«CS» Code
Opposite
Owner	«CS» Code
Owning Association
Owning Template Parameter
Qualified Name	FHIM::Datatypes::Code::originalText
Stereotype
Template Parameter
Type	String
Upper	1
Upper Value	(1)
Visibility	Public

 userSelected

Public Boolean userSelected

"Indicates that this coding was chosen by a user directly - e.g. off a pick list of available items (codes or displays)." - HL7 FHIR, Coding.userSelected

Constraints:

Properties:

Aggregation	None
Alias
Association
Association End
Class	«CS» Code
Datatype
Default
Default Value
Is Composite	false
Is Derived	false
Is Derived Union	false
Is Leaf	false
Is Ordered	false
Is Read Only	false
Is Static	false
Is Unique	true
Keywords
Lower	0
Lower Value	(0)
Multiplicity	0..1
Name	userSelected
Name Expression
Namespace	«CS» Code
Opposite
Owner	«CS» Code
Owning Association
Owning Template Parameter
Qualified Name	FHIM::Datatypes::Code::userSelected
Stereotype
Template Parameter
Type	Boolean
Upper	1
Upper Value	(1)
Visibility	Public