Summary

Information about the property PATCH

Synopsis

When running a patch you can expect the Windows Installer property "PATCH" is set at runtime. This is done when Windows Installer determines a patch is running. From the Windows Installer documentation find:

"The installer sets the PATCH property to a list of patches being applied by calling MsiApplyPatch, MsiApplyMultiplePatches or the /p Command Line Option. You can also set the PATCH property on the command line while installing a package using MsiInstallProduct or the /i Command Line Option." 

Discussion

The property PATCH can be used as a condition during the patch installation and to help you determine that you are running an installation as a patch.
The property MSIPATCHREMOVE can be used as a condition during a patch uninstall.

Additional Information

Reference:

• PATCH property
•  MSIPATCHREMOVE property

For additional information reference the most common conditionals/properties here: Common MSI Conditions Cheat Sheet