This download is a structure file to organize Microsoft Visual Studio projects. The SLN - Visual Studio Solution File file contains plain text information on the environment and progress of the project.
Upon opening preSolution, Project and postSolution information is extracted from the SLN file. The data extracted is then used to load the solution, projects with in the solution as well as persistent information that was attached to the solution. These files are similar to .VBG files that are used in the Microsoft Visual Studio program, Visual Basic.