This document specifies the requirements, test methods, inspection rules, marking and documentation, packaging, transportation and storage of oxalic acid (oxalic acid) by-product of D-p-hydroxyphenylglycine methyl ester. This document is applicable to the oxalic acid solution produced in the glyoxylic acid process of D-p-hydroxyphenylglycine methyl ester intermediate, and the by-product oxalic acid obtained after cooling, crystallization and centrifugation. It is mainly used in mining cleaning agents, precipitants, and color printing and dyeing. Agents, etc.