Office Open XML (OOXML) is a zipped XML-based file format developed by Microsoft for office documents, standardized by Ecma International as ECMA-376 and by ISO/IEC as ISO/IEC 29500. The standardization process was controversial, with critics arguing OOXML was unnecessary given the existing OpenDocument Format, and concerns raised about Microsoft's influence over the voting process. Microsoft provided patent covenants and added OOXML to its Open Specification Promise to address licensing concerns.