Re: [issue 6432] - a modest proposal

<Subscribe>
    <NotifyTo .../>
    <Format .../>
    <EndTo .../>
    <Expires .../>
    <Filter .../>
    xs:any
</Subscribe>

would do it for me.
then if dome spec choses to insert a <someNS:whatever>...</ 
someNS:whatever>
and include a mU for their extension, it could be extended any way  
they wish.

The argument supporting inclusion of a <Delivery>...</Delivery> might  
make it palatable for folks who might want that element to be in the  
wes namespace, but in since most of the stuff contained in that  
element will be in their own namespace, I think it is better to omit  
it so that Delivery clearly is in the namespace of the extender

-bob