a <#revenue=revenue stamp> documenting payment of federal tax on a commodity. The government sold these stamps to many companies. The categories of products requiring a proprietary stamp were: medicines, matches, perfumes and cosmetics, playing cards and photographs. See also <#privdie=Private Die Proprietary Stamps>, which were produced exclusively for a single user. <#scott=Scott> numbers are generally prefixed with RB although some are prefixed with R.