You can put MSBuild property files in this folder to override the default build configuration for Aegisub's build system. A number of sample files are provided. These can be copied and used as templates for common configuration. Importantly, configuring the location of several library dependencies. The copied sample files should be renamed to *.props, otherwise they will not be found by the build system. You should not check files placed in this folder into source control. Files must be named *.props to be found by the build system.