null

Indicates that a property has no value 

String

Represents the most common data type. String values are usually represented by an instance of the Java String class. Some components are values of any class. These are implicitly coerced to strings with the toString method.

Unless otherwise specified, you can assume that all properties are of type string.

Example: <String>Hello World</String>

List of string

Indicates that the value is expected to be a list of one or more strings. In Java, this value is always implemented as an instance of the List class. The elements of the list are then expected to be instances of the String class.

Example:

<List>
   <String>choice one</String>
   <String>choice two</String>
</List>