This method of accounting, which makes adjustments to the existing national account indicators, found traction in the System of Integrated Environmental and Economic Accounting (SEEA), published by the United Nations as an appendix to the 1993 SNA. The report offered five approaches, or versions, to developing environmental accounts. Over the years, the SEEA has been expanded and revised in view of the increased sophistication of accounting methodologies and technology. This revision will be explored in greater detail in the "Global Initiatives" section. Ultimately, the importance of the SEEA with respect to the green GDP is that it is possible to create full-sequence accounts from which aggregates such as green GDP can be derived and compared internationally, and many countries have begun this process.