17.1 Limitations of Instruction Files

It is worth mentioning a few limitations of Instruction Files before jumping into the specifics of their usage.

In order to update the value of an existing XML element, the <update-element-value> Instruction File element is used. The prerequisite, however, is that the XML element that is being updated should not contain any child element(s).

For example, if <update-element-value> is used to update a <BOOK> XML element, then the <BOOK> element should not have any child elements. The following <BOOK> element cannot be updated:

<BOOK>
<AUTHOR></AUTHOR>
</BOOK>

On similar lines, <update-element-value> works fine if and only if the XML element being updated is not empty. In short, it has some text existing in the element (which might include white spaces). The following <BOOK> element cannot be updated:

<BOOK></BOOK>

However, the following XML element is a valid candidate for...