Foundation Component is a collection of ALL ICD entities like diseases, disorders... It represents the whole ICD universe.
In a simple way, the foundation component is similar to a “store” of books or songs.
From these elements we build a selection as a linearization.
This analogy may however be misleading because there are many links between the ICD entities (like parent-child relations and other).
The ICD entities in the Foundation Component:
are not necessarily mutually exclusive
allow multiple parenting ( i. e. an entity may be in more than one branch, for example tuberculosis meningitis is both an infection and a brain disease)
A linearization is a subset of the foundation component, that is:
Fit for a particular purpose: reporting mortality, morbidity, or other uses
Jointly Exhaustive of ICD Universe (Foundation Component)
Composed of entities that are Mutually Exclusive of each other
Each entity is given a single parent
Linearizations are similar to the classical print versions of ICD Tabular List (e.g. volume I of ICD-10 or other previous editions).
Various linearizations could be built at different granularity,
use case or other purposes such as for Primary Care, Clinical Care or Research. The linkage from the foundation component to a particular
linearization will ensure consistent use of the ICD.