You are asking for OBR.4
value, Universal Service ID which contains the code and description of what panel or test are being ordered.
The panel will serve one single code and not the code of the component tests included in the panel.
Read this for more information
4.5.1.4 Universal service ID (CE) 00238
Components: <identifier (ST)> ^ <text (ST)> ^ <name of coding system (ST)>
^<alternate identifier (ST)> ^ <alternate text (ST)> ^ <name of alternate coding system (ST)>
Definition: This field is the identifier code for the requested observation/test/battery.This can be based on local and/or "universal" codes. We recommend the "universal"procedure identifier. The structure of this CE data type is described in the control section.