Methods for product data management and corresponding systems and computer-readable mediums. A method includes maintaining a hierarchical data structure for a complex item. The data structure includes a root node representing the complex item, at least one assembly node associated with a the partition node, and a plurality of part nodes each associated with the assembly node. The method includes defining at least two occurrences associated with the root node and corresponding to at least the root node and assembly node. The method includes defining at least one partition node representing a partition of the complex item, the partition node representing an organizational division of the occurrences of the associated with the root node that can be referenced in queries and navigation. The method includes associating at least two of the plurality of occurrences with the at least one partition node.