Sun Java System Web Server 7.0 Developer's Guide to Java Web Applications


Elements can contain subelements. For example, the following file fragment defines the cache element:

<!ELEMENT cache (cache-helper*, default-helper?, property*, cache-mapping*)>

The ELEMENT tag specifies that a cache element can contain cache-helper, default-helper, property, and cache-mapping subelements.

The following table shows how optional suffix characters of subelements determine the requirement rules, or number of allowed occurrences, for the subelements.

Table A–1 Requirement Rules and Subelement Suffixes

Subelement Suffix 

Requirement Rule 


Can contain zero or more of this subelement.


Can contain zero or one of this subelement.


Must contain one or more of this subelement.

element (no suffix)

Must contain only one of this subelement.

If an element cannot contain other elements, EMPTY or (#PCDATA) appears instead of a list of element names in parentheses.