This tutorial describes the following basic features:
•How to display or hide a control or table-row based on a condition
•How to make an edit field editable based on a condition
•How to display a message based on a condition
The mechanism essentially works as follows:
1.The user typically enters a value that will be used to determine whether a condition evaluates to true or false. Alternatively some other aspect of the document could be checked that does not depend on user input (such as whether some data node is empty or not).
2.The Visibility property of a control, table-row, table-column, or table can be set to true or false via an XPath expression that evaluates a condition. The Visibility property determines whether the object is displayed or hidden.