Centers for Midicare and Medicaid Services (CMS)

National Center for Health statisitcs (NCHS)

American Health Information Management Association (AHIMA)

American Hospital Association (AHA)

Encloses synonymus, alternative words, or explanatory parases

Found in the Tabular List and Index

Encloses supplementary words (nonessential modifiers) that may be present or absent in the statement of a disease or procedure without affecting the code assignment

Found in both Alphabetic Index and the Tabular List

Must be modified by an additional term to complete the code decription. 

Tabular List