The MDL in the RoHS test report is the minimum detection limit of the equipment for the substance, that is, the minimum content that can be detected, the content of the substance in the sample is lower than this limit when the equipment does not detect it, which is reflected in the report on the top of the ND, and by the same token, the report shows that the substance is ND, it does not mean that the sample does not contain the substance, but may contain it, but the content is very low, and it may not contain it. It may contain, but the content is so low that the equipment can not be detected
MDL is the acronym for Minimum Detection Limit, which is the smallest value that can be measured by the machine. It is equivalent to a straightedge with a minimum scale of 1 millimeter.