https://secure.ssa.gov/poms.nsf/lnx/0426510015
The diagnosis codes are general. Some less common specific diagnosis may be coded under a generic code since there may not be a diagnosis code for that specific illness.
A person can have only one or two diagnosis codes listed in the summary of the finding of disability and on the computer record even if they have 5 or 10 illnesses or conditions.
The ALJ can write paragraphs and paragraphs, but the computer record holds one or two codes.