DW templates and Contribute API
It turns out there are Dreamweaver templates and Contribute templates, and the two are not the same thing. According to DW documentation, you must use a DW template to create a file if you want Contribute to recognize instructions for editable and non-editable areas in the document. It looks like the presence of the InstanceBegin and InstanceEnd comments are the critical factor.
To get contribute to recognize instructions, you need an InstanceBegin comment immediately following the html declaration and an InstanceEnd comment immediately preceding the close html declaration, i.e.:
<html xmlns="http://www.w3.org/1999/xhtml"><!-- InstanceBegin -->
<!-- InstanceEnd --></html>
To make an area editable, enclose it in InstanceBeginEditable comment with a unique name attribute, e.g.:
<!-- InstanceBeginEditable name="EditRegion1" -->
<p>I have edited this in dw. and this bit in Contribute. </p>
<!-- InstanceEndEditable -->
As far as I can see no other files need to be present, let alone be in any state or contain any specific information.