Medical Coding ICD-10-PCS is the newest procedure coding system. There are a total of 72,081 codes included in ICD-10-PCS. Each of the seven alphanumeric characters used in each code represents something specific. A chart would be very beneficial in trying to decipher what each code's letter or number represents. For example, the first number of the code represents the type of service that was rendered. Other characters used represents a body system, body part or region, root operation, etcetera.