Pet peeve: for ambiguous currency signs, the currency code must always be clearly mentioned on the invoice. I hate it when I buy from companies in the US and t

Pet peeve: for ambiguous currency signs, the currency code must always be clearly mentioned on the invoice. I hate it when I buy from companies in the US and they just write their prices as $. Then my accountant doesn't know if that invoice was in USD or HKD. There are dozens of countries that use the $ as their currency symbol. At least mention the currency code somewhere, please.