Does the complete XML have to be supplied for MWS categories (i.e. ProductData)?

Amazon has a lot of categories. The products that I am working with only have two categorizable properties - size and colour, no further data is available to me (except title, description and shipping related details like size, weight etc.) Would it be possible to just use the following XML for all categories:

(Xml removed)
<ProductData>
 <CategoryName>
   <ProductType>ProductType</ProductType>
   <Color>Color</Color>
   <Size>Size</Size>
 </CategoryName>
</ProductData>
(Xml removed)

And then just replace CategoryName, ProductType, Color and Size with the correct values?

If other properties are required then are there a minimum set of required properties across all categories or do they differ?

Thanks,

Joe