OpenSolaris is an open source computer operating system based on Solaris created by Sun Microsystems, now a part of Oracle Corporation. It is also the name of the project initiated by Sun to build a developer and user community around the software.
OpenSolaris is a descendent of the UNIX System V Release 4 (SVR4) codebase developed by Sun and AT&T in the late 1980s. It is the only version of System V available as open source. OpenSolaris is developed as a combination of several software consolidations which were open sourced subsequent to Solaris 10. It includes a variety of free software, including popular desktop and server software. Sun has announced that future versions of its commercial Solaris operating system will be based on the OpenSolaris project.
The version here is build 135, downloaded from http://src.opensolaris.org/source/