With the increasing popularity of semi-structured documents (particularly in the form of XML) for knowledge management, it is important to create tools that use the additional information contained in the markup. Although research on textual XML retrieval is still in its early stages, many retrieval approaches and engines exist. The use of inline markup in these engines so far is very limited. We introduce the concept of element relationship and describe how it can improve similarity calculation. We illustrate our ideas with examples based on an existing document collection.