installerlevel

Installerlevel is a concept used in software installation and deployment to denote the depth, scope, or priority of an installation. It is typically implemented as a numeric value that gates whether particular components, features, or steps are installed or executed. The mechanism enables modular or staged installations, allowing administrators or users to tailor the installed footprint by selecting broader or more minimal configurations.

In Windows Installer, the closest established mechanism is the InstallLevel (INSTALLLEVEL). Features can specify a Level attribute, and during installation Windows Installer installs only those features whose Level is less than or equal to the current INSTALLLEVEL. The default INSTALLLEVEL is 1, but it can be adjusted via command-line options or transforms to enable additional components. For example, a product might install core components at level 1 and optional documentation or developer tools at higher levels. The Level gating interacts with feature selection and can influence which components are processed during the install sequence.

Other packaging systems may implement similar concepts under different names, such as install profiles, component tiers, or feature flags. The underlying purpose is consistent: to provide flexible, staged installation flows and to reduce footprint by enabling or disabling certain components based on a chosen level.

Implementation practices vary by framework, but common elements include a default level, explicit Level attributes or variables, and conditional execution of install steps based on the current installerlevel value. See also Windows Installer, MSI, feature, and modular installation concepts.