A repository index records the position of document entries relative to landmark entries within the document. Landmark entries are selecting using a landmarking policy and their position relative to the document are stored in a landmark directory. During index updates, an edit transcript is generated describing the difference between old and new document versions, and both the document repository index and the landmark directory are updated as needed. Thus, the number of update operations preformed as compared with conventional indexing techniques may be substantially reduced when small, localized changes are made to the document. This is due to fact that the positions of document entries are recorded relative to the landmark entries rather than the document itself. By doing so, the document index becomes more shift-invariant, requiring fewer update operations when entries are added or inserted in localized areas of the document.