Please note that the content of this book primarily consists of articles available from Wikipedia or other free sources online. A National Stock Number (NSN) is a 13-digit numeric code, identifying all the ''standardized material items of supply'' as they have been recognized by the United States Department of Defense. Pursuant to the NATO Standardization Agreements (STANAGs), the NSN has come to be used in all treaty countries, where it is also known as a NATO Stock Number. However, many countries that use the NSN progamme are not members of NATO, e.g. Japan, Australia and New Zealand. A two-digit Material Management Aggregation Code (MMAC) suffix may also be appended, to denote asset end use but it is not considered part of the NSN. An item having an NSN is said to be "stock-listed".