GCC Standardization Organization. GCC Standardization Organization (GSO) is a Regional Standardization Organization (RSO) which was established by the resolution of the GCC Supreme Council (22nd Session, Muscat, Oman, 30-31 December 2001) and assumed its operation in May 2004 with membership of the governments of The State of the United Arab Emirates, The Kingdom of Bahrain, The Kingdom of ....