What does SAK stand for?

In Visual Studio/SQL Server Management Studio, when you add a solution/project into source control, the solution/project file will be updated to include the source control integration info. If you open up with notepad a project file, you may notice 4 strings that have all "SAK" values.

< SccProjectName>SAK< /SccProjectName>
< SccAuxPath>SAK< /SccAuxPath>
< SccLocalPath>SAK< /SccLocalPath>
< SccProvider>SAK< /SccProvider>

After a solution/project is added into source control successfully, a file named mssccprj.scc, which keeps the binding info, will be generated in the solution/project local folder.

SAK is a flag that tells Visual Studio/SSMS the project is under source control, and the real bindings are persisted in the mssccprj.scc files. So, Visual Studio/SSMS reads them from there and uses them when needed.