This code system http://terminology.hl7.org/CodeSystem/rcFB defines many codes, but they are not represented here

 <status value="active"/> <experimental value="false"/> <date value="2019-03-20T00:00:00-04:00"/> <publisher value="TBD - External Body"/> <contact> <name value="Paul Frosdick, NHS Information Authority"/> </contact> <description value="The Read Codes Four Byte Set consists of 4 alphanumeric characters. This version contains approximately 40,000 codes arranged in a hierarchical structure. Top level hierarchy sections: Disorders Findings Surgical procedures Investigations Occupations Drugs"/> <content value="not-present"/> </CodeSystem>