Addressing spans

As I read the draft, there's no way for a locator to address a span of
elements, despite a number of statements to the effect that resouces
need not be points.  Have I missed something, or is there a gap here?
I think spans are absolutely crucial for stand-off annotation,
e.g. what I write now in our local normalised SGML as

<sentence from='(ID) w37' to='(ID) w52'></sentence>

with an inclusion semantics, so this is processed as

 <word id=w37>Now</word>
 <word id=w38>is</word>
 . . .
 <word id=w52>country</word>