|
Occurrence Indicator
|
Description
|
|---|---|
|
None
|
The element must appear once and only once. Neither optional nor repeatable.
|
|
?
|
The element (or group of elements) may appear zero or one time. The element is optional, but is only allowed to appear once. Optional but not repeatable.
|
|
+
|
The element (or group of elements) must appear one or more times. The element is required to appear at least once, but multiple consecutive occurrences may be present. Repeatable but not optional.
|
|
*
|
The element (or group of elements) may appear zero or more times. The element can appear as many times consecutively as needed. Repeatable and optional.
|