RGS

RGS is a feather-light command-line utility which consists of an executable file for .RGS (Registrar) scripts. What it does exactly is use the RGS file as an argument to execute the script inside.
The downloaded package contains the apps executable file along with a Readme document. You can simply double-click the .exe to immediately register the tool without any further user assistance.
In the command-line interface, the usage is RGS [ = ] [...]] [/c] [/u], where = represents the %MODULE% used in the .RGS, along with its replacement value. /c means console mode, while the /u command line can be used to unregister the program.
A .RGS file is a text file that includes a script for adding, editing or deleting Windows registry entries. This type of syntax is automatically generated for your COM server by the ATL Control Wizard. While REG files rely on APIs, RGS items use data to gain access to the registry. The key difference is that using the RGS syntax is more efficient than the classical REG file syntax. During a servers installation, the Script Engine is automatically called by ATL to process the RGS at runtime.