Dave Winer (who sees namespaces as one factor that divides programming-XML from literary XML) opines, "There is no equivalent of namespaces in prose or poetry." He's making a good point about the remarkable variety of things different people see in XML.
But, of course, there are namespaces in prose and poetry.
Once upon a time, ...
We use all sorts of cues in prose (and especially in poetry) to establish what things that come later are going to mean. Notoriously, an American war story begins with a claim to having the real, inside information:
Now, this is the straight dope. One time...
When the patrol winds up in the parlor with the priest, the prostitute, and the policeman, all hiding from the panzer, we know precisely what kind of dope we're drinking with.
This isn't genre -- it's not formal, it's not establishing the shape of the tale. It's about setting vocabulary and linguistic expectation -- it's a namespace. Same thing with dialect in poetry; when Robbie Burns begins
THERE was a lass, they ca’d her Meg
we know that we're in a different place than when Donne sets out
"Tis true, 'tis day; what though it be?
O wilt thou therefore rise from me?
We're in roughly the same place here -- sex and work -- but we need the cue to establish how to interpret the simple words.