Published: May 2010
Microsoft SharePoint Foundation provides new members that make it possible for you to upgrade custom Features through versioning and declarative upgrade actions. As a result, you can perform the following kinds of modular upgrades to Features in SharePoint Foundation:
Define upgrade definitions for new Feature versions.
Provision a list instance as part of a Feature upgrade.
Create separate upgrade action sets, based on the Feature version, that remove different sets of files.
Apply settings to site collections where a particular Feature is activated.