MII is the first digit of a credit/debit card number. The MII identifies the type of the issuing institution. American National Standards Institute (ANSI) and the International Organization for Standardization (ISO) developed a numbering system to identify institutions that issue payment cards. Financial payment cards, such as those branded with Visa and MasterCard logos are mostly issued by banks and so fall into the category of payment networks. Industry Identifier (MII). It’s used to identify which industry the card was issued by. The MII digits are:

Here is a table of the list of MII types:

MII DIGIT VALUE ISSUER CATEGORY
0 ISO/TC 68 and other industry assignments
1 Airlines
2 Airlines, financial and other future industry agreements
3 Travel and entertainment
4 Banking and financial
5 Banking and financial
6 Merchandising and banking/financial
7 Petroleum and other future industry assignments
8 Healthcare, telecommunications, and other future industry assignments
9 For assignment by national standards bodies