In most instances, both the sender and the receiver will need to map standard codes that are used in the HL7 message to local codes used by the native system (i.e., the EHR or LIMS). A mapping workbook that lists out all the required and optional data elements in the message will facilitate the review and collection of this information. The technical team will then be able to use the mapping workbook to populate lookup tables and update system code as necessary to generate the message. Building Blocks developed a Mapping Workbook for the LOI order message and the LRI result message.