This document defines terms and general requirements for evaluating the quality of nucleic acids used in multiplex molecular tests that detect multiple target sequences simultaneously. Applicable to both qualitative and quantitative in vitro diagnostic (IVD) methods and laboratory-developed tests (LDTs), it provides guidance for detecting human or microbial nucleic acid targets in clinical specimens. It supports medical laboratories, IVD developers, biobanks, research institutions, and regulatory authorities in ensuring reliable molecular testing. This document does not cover metagenomics. Laboratory-developed or in-house tests refer to examination procedures developed for a laboratory's own use.