Word with number that is one of the conventions used in the diagnostic code book titled International Classification of Diseases, Tenth Revision, Clinical Modification (ICD-10-CM) . This indicates that the code excluded should never be used at the same time as the code above the Excludes 1 note. An Excludes 1 is when two conditions cannot occur together (e.g., congenital form versus acquired form of a condition). A note instructs the reader to go to another code for the excluded condition. This convention does not appear in the former ICD-9-CM code books.