Methods for product data management and corresponding systems and computer-readable mediums. A method includes maintaining a data structure for a complex item. The data structure includes a root node representing the complex item, at least one assembly node associated with the root node, and a plurality of part nodes each associated with the assembly node. The method includes defining at least two absolute occurrences associated with the root node and corresponding to at least the root node and the assembly node. The method includes defining at least one managed occurrence that includes a plurality of the absolute occurrences. The method includes using the managed occurrence as a central control authority for the plurality of absolute occurrences.