Many business operations feature hierarchical data. For example, business users need to manage human resource (HR) hierarchies, which model the relationship between employees. When hierarchical data changes or versions of a data item are independently modified, it is useful to compute the differences between the old and new hierarchical data in order to reconcile or display the changes. The changes are often expressed as a so-called edit script: a compact sequence of operations that transforms one tree of hierarchical data into another. A sequence of edit scripts may therefore represent the version history of given hierarchical data.