DOCBOOK: Use of <varargs> and <paramdef>

[John dot Himpel at edwardjones dot com]

I am trying to markup the following text:

   ... Begin Text ...

void LoaderReqSymLists (const char **symbol0, ... )

This function allows the registration of the required symbols with the loader.
The function takes one or more NULL terminated lists of symbols.
The end of the argument list is indicated by a NULL argument.

   ... End Text ...

I tried marking up the above like this:

<funsynopsis>
<funcprototype>
<funcdef>void <function>LoaderReqSymLists</function></funcdef>
<paramdef>const char <parameter>**symbols</parameter></paramdef>
<varargs />
</funcprototype>
<funcsynopsis>

This failed validation.  So I dug out my TDG and looked at funcprototype.
My reading of the TDG indicates that I cannot mix <void> <varargs> and <paramdef>'s within a single 
<funcprototype>.

Is my attempted markup logical or is the DTD more logical?

What is the "proper" way? 

Thanks.

John