Sets whether the Visual Merge feature is used when merging files.
Visual_Merge = {Yes|No|Only if there are conflicts}
Instructs VSS to use the Visual Merge feature only when conflicts between changes in the two files being merged exist, otherwise use the standard merge:
Visual_Merge = Only when there are conflicts
You can also set this variable using the Use Visual Merge check box on the General tab of the Tools Options dialog box.