The method reference is managed by the reporting lab and identifies the standard operating procedure used for generating the reported dataset. The standard operating procedure is a document that describes setup and steps necessary to make a comparable measurement, e.g. inlet design, sample flow, sample conditioning, calibration procedures, data processing steps, ... . Since the method reference is managed by the reporting lab, it needs to begin with the lab code. Any change in instrument setup or data handling that could make the time series incomparable needs to result in use of a new method reference (will register as new time series in database).
Method ref: NO01L_IC
Method ref: <lab code>_<unique reference to lab internal SOP>