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Arepresents an association between two.

Eachis identified by a uniqueId and is distributed as a row in the Relationship file.

Acontainsof two logically associatedand theof anotherthat indicates theby which they are associated.

Table 1. Example: Defining arthritis as a type of joint disorder




In human readable terms...

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Relationships and concept definitions

Eachinis logically defined through itsto other.

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

Example: |Fracture of tarsal bone (disorder)| is defined as:

Note: Ais assigned only when thatis 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 |Streptococcal sore throat (disorder)| as having |causative agent| |Streptococcus pyogenes (organism)| . Instead it is correctly defined as having the more general |causative agent| |Genus Streptococcus (organism)| .

IS A Relationships

|is a| are also known as "Supertype -" or "Parent -". |is a| are the basis of's hierarchies, as illustrated below.

Figure 2. Example IS A hierarchy

Acan have more than one |is a| to other. In that case, thewill have parentin more than oneof a top-level.can be multi-hierarchical.

Figure 3. Example IS A Relationships

Attribute Relationships

Anis an association between twothat specifies aof one of the(the source of the). Eachhas a name (the type of) and a value (the destination of the).

The combination of theand |is a| associated with arepresent the logical definition of that. Therefore, the logicaldefinition includes one or more supertypes (represented by |is a| ), and a set of definingthat differentiate it from the otherdefinitions.


Since pneumonia is a disorder of the lung, the logical definition of the |Pneumonia (disorder)| inincludes the following. The |Finding site| is assigned the value |Lung structure (body structure)| .

The full definitions of the |Pneumonia (disorder)| ,|Infective pneumonia (disorder)| and |Bacterial pneumonia (disorder)| are shown below. Each line represents a definingwith a value.

Figure 4. Definition of |Pneumonia (disorder)|

Figure 5. Definition of |Infective pneumonia (disorder)|

Figure 6. Definition of |Bacterial pneumonia (disorder)|

illustrates some of thesegraphically. |is a| relate ato more generalof the same type. In contrast,(such as |Finding site| and |Causative agent| ) relate ato relevant values in other branches of the.

Figure 7. Illustration of Defining Relationships

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