Integrated baseline reviews have their foundation in EVM. IBRs have been required of earned value programs since the early 1990s when product divisions and acquisition centers had their own processes for conducting these reviews. Over the next decade, IBR guidance continued to evolve from a variety of sources. In 1996, the DoD Earned Value Management EVM Implementation Guide EVMIG was published. In 1999, an Air Force IBR process was released. In 2003, the National Defense Industrial Associations NDIA Program Manager Guide to IBRs was developed and subsequently endorsed by DoD. In 2006, the EVMIG was updated. In 2010, the NDIA IBR document was updated. While the IBR process evolved through a variety of guidance documents, the application of the process was far from uniform.