InstallMate sets this variable to the primary installation folder of any existing installation of the same product. If the product is not currently installed, this variable is empty.
The major uses for this variable are:
- Detection of the installation folder of the previous version of the same product, for example during upgrades.
- Detection of the presence of a previous version of the same product.
In this context, "same product" is defined as "product with the same UninstallKey value" (which in turn is typically defined as <ProductCode>). As long as you build your installers for a given product from the same InstallMate project file and change neither the Product GUID attribute on the Product info project page nor the value of the UninstallKey variable, the resulting installers will be for "the same product".
Note: InstallMate and MSI-based installers set the required registry key for this variable, but not all third-party installers do. Therefore, if the previous version of your product was installed with a non-Tarma and non-MSI installer, this variable might be empty even if a previous version of the product is present on the target system.
Tip: As a more reliable detection of the presence of a previous version of your product, you can use the InstalledVersion variable.
You can refer to this variable as <InstallLocation>. In conditional expressions you can omit the brackets and simply use InstallLocation as a test for previous product installation. Do not change its value; it has been carefully configured for cross-platform compatibility.