A represents an association between two .

Each is identified by a unique Id and is distributed as a row in the .

A contains of two logically associated and the of another that indicates the by which they are associated.


Example: Defining arthritis as a type of joint disorder

Relationship.id

sourceId

typeId

destinationId

In human readable ...

Relationships and concept definitions

Each in is logically defined through its to other .

Every (except the ) has at least one to a supertype . and defining attribute are known as the of . They are considered defining because they are used to logically represent a by establishing its with other . This is accomplished by establishing with one or more defining (called supertypes) and modeling the difference with those supertypes through defining attributes.

Example: is defined as:

Note: A is assigned only when that is always known to be true.

Example: Group A Streptococcus causes most cases of Streptococcal pharyngitis. However, a small percentage of these cases are caused by other species of Streptococcus. Therefore, it would be incorrect to define  as having   . Instead it is correctly defined as having the more general .

IS A Relationships

are also known as "Supertype - " or "Parent - child relationships". are the basis of  hierarchies, as illustrated below.


Example IS A hierarchy


A can have more than one to other . In that case, the will have parent in more than one of a top-level . can be multi-hierarchical.


Example IS A Relationships


Attribute Relationships

An is an association between two that specifies a of one of the (the source of the ). Each has a name (the type of ) and a value (the destination of the ).

The combination of the and associated with a represent the logical definition of that . Therefore, the logical definition includes one or more supertypes (represented by ), and a set of defining that differentiate it from the other definitions.

Example:

Since pneumonia is a disorder of the lung, the logical definition of the  in includes the following . The  is assigned the value .

The full definitions of the concepts  ,  and  are shown below. The first lines in each example refer to   of the defined concept. Each of the subsequent lines refines the definition by specifying an  with a value.

=== 95436008 |Lung consolidation (disorder)| + 
       205237003 |Pneumonitis (disorder)| :
            { 116676008 |Associated morphology (attribute)| = 707496003 |Inflammation and consolidation (morphologic abnormality)|, 
              363698007 |Finding site (attribute)| = 39607008 |Lung structure (body structure)| }
Definition of |Pneumonia (disorder)|
=== 128601007 |Infectious disease of lung (disorder)| +
       233604007 |Pneumonia (disorder)| :
            { 370135005 |Pathological process (attribute)| = 441862004 |Infectious process (qualifier value)|, 
              116676008 |Associated morphology (attribute)| = 707496003 |Inflammation and consolidation (morphologic abnormality)|, 
              363698007 |Finding site (attribute)| = 39607008 |Lung structure (body structure)| }



Definition of |Infective pneumonia (disorder)|



=== 312119006 |Bacterial lower respiratory infection (disorder)| +    /
       312342009 |Infective pneumonia (disorder)| :
            { 370135005 |Pathological process (attribute)| = 441862004 |Infectious process (qualifier value)|, 
              116676008 |Associated morphology (attribute)| = 707496003 |Inflammation and consolidation (morphologic abnormality)|, 
              363698007 |Finding site (attribute)| = 39607008 |Lung structure (body structure)|, 
              246075003 |Causative agent (attribute)| = 409822003 |Superkingdom Bacteria (organism)| }



Definition of |Bacterial pneumonia (disorder)|


 illustrates some of these graphically. relate a to more general of the same type. In contrast,  (such as  and ) relate a to relevant values in other branches of the .


Illustration of Defining Relationships


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