Available message types in JMS?

Question

This is based on a past exam question.

The question is asking to describe the four types of message available using JMS.

The problem is it says the four, not just four. So it assumes their is only four, no more no less.

However according to this site their seems to be five;

1. streams
2. maps
3. text
4. objects
5. bytes

*Another book states that XML is another potential type in future versions of JMS. Is XML already available?

Am I missing something or is the question just wrong?

Thanks.

EDIT: There are 5 types

Answer 1

Sun's JMS Spec 1.1 in Section 3.1.1 lists the same five message types. The question appears to be wrong.