What’s New > Windchill > 12.0.1.0 > Deployment and Configuration > Optionally Enabled Control is Disabled
  
Optionally Enabled Control is Disabled
Product: Windchill
Release: 12.0.1.0
Summary
Starting with Windchill 12.0.1.0, all new features in your Windchill solution are enabled by default. The Release.optIn property, which was used to control new features, has been disabled from this release.
Going forward, any new feature control will be determined on an individual basis. The visibility and use of features may be controlled using properties or preferences, or other appropriate mechanisms.