086 - Government Document Classification Number

This tag is where you will find the classification number assigned to a government document by a government agency at any level (e.g., provincial, state, national, international). 

Federal Documents in the U.S. are managed through GovInfo and the most common classification you will find in the 086 tag is a United States Superintendent of Documents (SuDOC) number (identified by a value of 0 in the 1st indicator). These numbers are different from GPO item numbers, which are used to manage distribution within the Federal Depository Library program, and are found in the 074 tag. 

The full classification number will be in subfield a (which is NOT repeatable).

A cancelled or invalid classification number would appear in subfield z.

If the first indicator contains a blank, that means that an agency other than GPO or the Canadian Government Printing Office created the number and the code identifying that agency will be found in subfield 2.

A record may contain multiple 086 tags, and multiple 074 tags. These should be in the same order as each other so you can easily tell which ones go together. 

Here is an example:

074         0621 (V.1)
074         0620 (V.2)
086  0     I 19.2:W 68/2
086  0     I 19.3:1620

Volume 1 has SUDOC number I 19.2:W 68/2 while volume 2 carries the number I 19.3:1620.