A good intro from blog.microsoft.com: http://blogs.msdn.com/recman/archive/2006/08/10/694087.aspx
After bar code policy is removed, the new files will not have bar code generated. But the existing ones will still keep the bar code values. The ‘View Properties’ window will still show the bar code image.
Customized barcode generator (sample here) indicates that barcode generator does NOT take any input parameter. So it’s impossible to embed any specific information about the target.