Figure 3.

Use of a coded element (CE) field in an OBX segment of the HL7 message. Field 4 of the OBX segment contains the Observation Identifier (what was observed) and is of type CE (Coded Element). Each CE type field consists of six parts, but only three parts are shown in this example. The first part of a CE field is the code, the second part is the description (meaning or text) of the code, and the third part is the coding scheme from which the code was selected. This example shows a LOINC coding (LN) being used as the observation identifier.