Character #1: always Alpha
The letter “U” is not used because it is easily confused for the letter “V”
Character #2: always Numeric
Character #3-7: are alpha or numeric
Some codes will use “x” as a place holder in character #4-7to hold it open for future expansion into that space (you MUST write that character if it exists in the code)
Character #7 is only used in certain chapters, many of which WILL have application in chiropractic (External Causes of Injury, Obstetrics, Injury, and Musculoskeletal)