Question on 2.1.2 - Message Types

Question on 2.1.2 - Message Types -

A signal message is characterized by the presence of an eb:SignalMessage
element in the ebMS header.
A user message is characterized by the presence of an eb:UserMessage element
in the ebMS header.

I know we have deferred speaking about bundling. I am curious though.
Section 2.1.2 seems to imply that an ebMS message could potentially be both
a Signal Message and an User Message. Is this the intent?

Thanks,
Ric