Environment levels and hierarchy

There are four levels of environment settings: application, tool, model, and model process. All levels contain the same environment variables and have the same effect on output results. They differ only in how you access and set them.

The four environment levels form a hierarchy where the application level is highest. In this hierarchy, environment settings are passed down to the next level, as illustrated below. At each level, you can override the passed-down environment settings with another setting.

The one exception to this hierarchy is with models. If you run the model from the ModelBuilder window, the application environment is passed down. If you run the model using its tool dialog box, the tool environment is passed down.

Environment hierarchy

There are four levels of environment settings:

  1. Application-level settings are the default and will be applied to any tool when it is executed.
  2. Tool-level settings are applied to a single run of a tool and override the application-level settings.
  3. Model-level settings are specified and saved with a model and override tool- and application-level settings.
  4. Model process-level settings are specified at the model process level, are saved with the model, and override model-level settings.