What is Hallmark Unique Identification (HUID) number in gold jewellery

According to the Department of Consumer Affairs website, hallmark consists of 3 symbols which give you some information. In this, the first symbol is the BIS logo, the second symbol indicates purity and fineness and the third sym​bol is the HUID.

from Personal Finance News-Wealth-Economic Times https://ift.tt/3re8Tc1