  XML has become the de-facto standard for data representation and exchange,
resulting in large scale repositories and warehouses of XML data. In order for
users to understand and explore these large collections, a summarized, bird's
eye view of the available data is a necessity. In this paper, we are interested
in semantic XML document summaries which present the "important" information
available in an XML document to the user. In the best case, such a summary is a
concise replacement for the original document itself. At the other extreme, it
should at least help the user make an informed choice as to the relevance of
the document to his needs. In this paper, we address the two main issues which
arise in producing such meaningful and concise summaries: i) which tags or text
units are important and should be included in the summary, ii) how to generate
summaries of different sizes.%for different memory budgets. We conduct user
studies with different real-life datasets and show that our methods are useful
and effective in practice.
