for the VAT identification number
ref:vatin is a tag to add the VAT identification number to an object (wikipedia, usually the number of the operator found on the receipt you get when you pay something). The usual syntax is <country-code><VAT-number>. See the linked wikipedia page for more information and the codes.
- ref:vatin=IT12345678901 for a business in Italy
- ref:vatin=DE115055186 for a business in Germany
You can attach this key to every business, usually it refers to the operator of the place. Some examples: