In this chapter, we have considered the general problem of mapping between XML documents and application data structures. In particular, we looked at mapping to trees, tables, and graphs. These are not the only techniques for mappingif you have written more than a few XML applications, you should have already accumulated a list of useful "patterns" of mapping. If and when these patterns become sufficiently frequent, it will be worth developing a tool for automating the mapping. Chapter 15 covers such tools.