PHPCR & Doctrine PHPCR-ODM Bundle for the Symfony Framework.
This bundle integrates PHP Content Repository implementations and the Doctrine PHPCR-ODM into Symfony2.
The Doctrine Project is the home of a selected set of PHP libraries primarily focused on providing persistence services and related functionality. The PHPCR-ODM project provides an Object - Document Mapper built on top of the content repository standard PHPCR.
It leverages the various features of PHPCR like references, children and parent relations and versioning and adds features of its own like multilanguage.
For information, see Symfony CMF Documentation, specifically Installing and configuring Doctrine PHPCR-ODM and DoctrinePHPCRBundle.
PHPCR-ODM in general is documented in the Doctrine PHPCR-ODM documentation.