It is not a function, it is a procedure that is described as follws :
The Integration Process
The procedure that follows is based on revision conflicts produced by two users. The integration process can merge changes between only two versions at a time; this process may be repeated to integrate the conflicts of multiple users.
The Revision Conflict
Imagine that you and another user have fetched the same revision of a part from a Pro/PDM product database and made different modifications to it. The other user has already submitted the object back to Pro/PDM and received approval for the changes that he or she made, and the modified object is now the latest revision in the product database.
When you attempt to submit your modified version of the object, Pro/PDM informs you that this revision of the object already exists in the product database. Pro/PDM provides you with two solutions.
If your design replaces the previously submitted version, you may continue to submit using the Pro/PDM command Override Errors. However, if you want to incorporate the changes made in the latest revision in the database, Pro/PDM provides you with tools to integrate these models.
Source and Target Objects
When you decide to integrate the changes between two revisions of the same object, you must use those revisions to prepare two versions of the object, a source object and a target object.
The source object is the revision of the object that contains unapproved changes that you want to have incorporated into the target object, which is the latest revision of the object in the product database.
Pro/PDM provides you with a process for creating a renamed version of the source object and fetching a copy of the target object, so that you can integrate the changes and create a new latest revision of the object without overwriting the original source and target objects.