XML by Example

The Secret of Plus, Star, and Question Mark

The plus (“+”), star (“*”), and question mark (“?”) characters in the element

content are occurrence indicators. They indicate whether and how elements

in the child list can repeat.

• An element followed by no occurrence indicator must appear once and

only once in the element being defined.

• An element followed by a “

+” character must appear one or several

times in the element being defined. The element can repeat.

• An element followed by a “

*” character can appear zero or more times

in the element being defined. The element is optional but, if it is

included, it can repeat indefinitely.

• An element followed ...