Established specifically for their intended use, pharmacopoeial reference standards are thoroughly characterised and their uses may go beyond those described in compendia, although a clear-cut distinction between quantitative use and qualitative use is essential. For example, compendial assay standards for APIs may be used for assay of finished products as long as specific criteria are fulfilled, as stated in chapter 5.12 of the European Pharmacopoeia (Ph. Eur.).