The attached file contains the basic IRS documentation for the BMF, including lists of all code values.
Ron Williams of the IRS EP/EO Division referred us to IRM 7820, a part of the Exempt Organizations/ Business Master File Handbook, for details on how data elements are coded on the BMF. This is probably NOT disclosable to the public.
The classification code (CLASSCD) is a secondary classification added by the IRS determination specialists, usually but not always consistent with the FOUNDATION CODE. An intentional inconsistency would be the classification of a religious college: The foundation code would reflect its status as an educational institution and it would have to file a 990 so its filing requirement code would NOT be religious. However, the IRS would want the religious connection to appear somewhere on the record and the CLASSIFICATION field is where that would be done.
Up to 4 different codes can be included in the CLASSIFICATION field.
The IRS EO/BMF Handbook lists the classifications (7820, Exhibit 10) and offers only a short description in 7820-16, 511.3 and 7820-27.
For example a c3 organization with the classification code 7200 is a religious/educational organization. (7=religous organization, 2=educational organization, and the zeroes are simply placeholders that mean nothing.)
The values for these codes are listed in the attached IRS BMF code book under "TABLE OF EO SUBSECTION AND CLASSIFICATION CODES".