| A | B |
|---|
| three-character category | Capital letter -> two digits or one digit and one letter -> |
| four-character category | three character category-> period or decimal and one number or letter |
| five-character category | three-character category -> period or decimal AND two additional characters |
| six-character category | three-character category -> period or decimal AND three additional characters |
| seven-character category | extension and final character in a code |
| Placeholder x | dummy X is a placeholder x used in conjunction with codes that require a 7th character extension |
| fourth digit in four-character category | provides more information or specific description of the condition. |
| fourth digit (8) in four-character category | .8 means the diagnostic statement may include some specific information and no other code is available |
| fourth digit (9) in four-character category | .9 usually means the diagnostic statement doesn't include enough information to choose a more specific code |
| five-character category are a subcategory | subdivision of a four-character subcategory code |
| six-character category are a subcategory | subdivision of a five-character subcategory code |
