1. Data structure associated with an hierarchical file system of a computational system, the hierarchical file system comprising a set of files arranged in a directory structure comprising a set of directories; the data structure comprising a data store; the data store comprising a set of reference data objects (topics) and a set of coupling data elements, wherein the set of coupling data elements comprise at least: one coupling data element for coupling a first item selected from either the set of reference data objects or the set of files or the set of directories with a second item from either the set of reference data objects or the set of files or the set of directories.