w

upgrade.txt

+- All framework classes are now namespaced, and the name prefix `C` is removed.
+
+- The format of path alias is changed to `@yii/base/Component`.
+  In 1.x, this would be `system.base.CComponent`. See guide for more details.
+
+- The root alias `@yii` now represents the framework installation directory.
+   In 1.x, this is named as `system`. We also removed `zii` root alias.
+
+
+- `CList` is renamed to `Vector`, and `CMap` is renamed to `Dictionary`.
+  Other collection classes are dropped in favor of SPL classes.
+