To further introduce the data-holder identification issues, we present an example of indexing by key.
The example is a mapper that uses indexing to identify the occurrences of data holders in both its input and its output. On the input side, the indexing matches the corresponding data from different parts of an XML structure. On the output side, the indexing finds the correct location of an element in an XML structure.
The example illustrates the use of:
In the following sections of the chapter, we will explain the detailed operation of these properties and components.