mixed="true" in explain

["Ray Denenberg, Library of Congress" <rden@loc.gov>]

Since we may be taking over the Explain schema ... I've been in touch with 
Mike Taylor and he has disavowed any ownership, and Rob is nowhere to be 
found.  I've been studying the schema and have run into the following 
question.

  Several of the definitions look like this:

<element name='host'>
<complexType mixed='true'>
</complexType>
</element>

What does it mean?

I know what mixed='true' means, so if for example, you had

<element name='host'>
<complexType mixed='true'>
<sequence>
<element name="a"/>
<element name="b"/>
</sequence>
</complexType>
</element>

Then you could have an instance of element <host> that would look like:

<host>
text preceding element a
<a>content of element a </a>
text between elements a and b
<b>content of element b</b>
text following element b
</host>

In other words, mixed content and elements, which would not be allowed 
without mixed="true"

 But what does the first mean?  The complex definition does not define any 
elements, and it seems to me that it degenerates to nothing more than a 
string.  I've tested it out and nothing else seems to make any sense.

Anyone have any other interpretations?

--Ray