This guide is applicable to the performance verification of clinical chemistry testing procedures by medical laboratories applying for accreditation or that have been accredited, and can also be used as a reference by assessors during on-site assessments. This guideline is mainly applicable to clinical chemistry quantitative testing methods used in medical laboratories. Quantitative testing procedures/methods used in other professional fields can be used as a reference. Clinical chemistry quantitative testing procedures, also known as clinical chemistry quantitative testing methods, are uniformly referred to as clinical chemistry quantitative testing procedures (hereinafter referred to as "testing procedures") in this guide. This guidance applies to validated testing procedures used by laboratories.