Back in December 2013, the OMB (Office of Management and Budget) published new guidance a 2 CFR Part 200 entitled Uniform Administrative Requirements, Cost Principles, and Audit Requirements for Federal Awards (OMB Uniform Guidance). The new guidance is often referred to as the "Super-Circular" even though technically, its not a circular. Its now part of the Code of Federal Regulations.
The new guidance became effective a year later, December 2014. The new OMB Uniform Guidance supersedes and streamlines requirements from OMB Circulars A-21 (Cost Principles for Educational Institutions), A-87 (Cost Principles for State, Local and Indian Tribal Governments), A-89 (Catalog of Federal Domestic Assistance), A-102 (Grants and Cooperative Agreements with State and Local Governments), A-122 (Cost Principles for Non-Profit Organizations), and A-133 (Audits of States, Local Governments and Non-Profit Organizations). Cost principles under OMB's Uniform Guidance apply to contracts with non-profits, educational institutions, state and local governments, and Indian tribal governments.
Now that OMB has consolidated and re-titled its administrative requirements, cost principles and audit requirements, the FAR (Federal Acquisition Regulations) require updating to replace obsolete references. The FAR Councils did that earlier this month. The first thing they set about doing was to find a shorter title than the official 2 CFR Part 200 title; Uniform Administrative Requirements, Cost Principles, and Audit Requirements for Federal Awards. They did this by adding a new definition under FAR 2.101. It is now simply referred to as "OMB Uniform Guidance".
In addition to the new definition, the final rule makes about twenty additional changes, removing specific references to OMB circulars and replacing them with the term "OMB Uniform Guidance". A goodly number of these changes impacted the cost principles found at FAR Part 31.
You can read the full text of the changes here.