The purpose of the GEMs is to create a useful, practical, code to code translation reference dictionary for both code sets, and to offer acceptable translation alternatives wherever possible. For each code set, it endeavors to answer this question: Taking the complete meaning of a code (defined as: all correctly coded conditions or procedures that would be classified to a code based on the code title, all associated tabular instructional notes, and all index references that refer to a code) as a single unit, what are the most appropriate translation(s) to the other code set.
The I-10 and I-9 GEMs are used to facilitate links between the diagnosis codes in I-9 volume 3 and the new I-10 code set. The GEMs are the raw material from which providers, health information vendors and payers can derive specific applied mappings to meet their needs.
The I-10 to I-9 GEM contains an entry for every I-10 code. Not all I-9 codes are contained in the I-10 to I-9 GEM; the I-10 to I-9 GEM contains only those I-9 codes which are plausible translations of the I-10 codes. The translations given are based on the I-10 code looked up, the source system code in the I-10 to I-9 GEM. The I-10 to I-9 GEM can be used to convert I-9 based systems or applications to I-10 based applications, or create one-to-one backwards mappings (also known as a crosswalk) from incoming I-10 based records to I-9 based legacy systems.