Mono is a software platform designed to allow developers to easily create cross platform applications. It is an open source implementation of Microsoft's .Net Framework based on the ECMA standards for C# and the Common Language Runtime. We feel that by embracing a successful, standardized software platform, we can lower the barriers to producing great applications for Linux. This is a legacy version of mono, the last stable release of the 2.10.x series. Certain programs are known to run well with this older version (such as opensim). You should try to run your program under the newer version on slackbuilds.org simply called 'mono' if you are unsure what version is required. THIS VERSION WILL CONFLICT WITH THE NEWER VERSION OF MONO.