The group adopted the Open Source Definition for open-source software, based on the Debian Free Software Guidelines. They also established the Open Source Initiative (OSI) as a steward organization for the movement. However, they were unsuccessful in their attempt to secure a trademark for 'open source' to control the use of the term. In 2008, in an apparent effort to reform governance of the organization, the OSI Board invited 50 individuals to join a "Charter Members" group; by 26 July 2008, 42 of the original invitees had accepted the invitations. The full membership of the Charter Members has never been publicly revealed, and the Charter Members group communicated by way of a closed-subscription mailing list, "osi-discuss", with non-public archives.