Halliday & Matthiessen (2014: 381):
… there is a progression in the nominal group from the kind of element that has the greatest specifying potential to that which has the least; and this is the principle of ordering that we have already recognised in the clause. In the clause, the Theme comes first. We begin by establishing relevance: stating what it is that we are using to introduce this clause into the discourse, as ‘this is where I’m starting from’ — typically, though by no means necessarily, something that is already ‘given’ in the context. In the nominal group, we begin with the Deictic: ‘first I’ll tell you which I mean’, your, these, any, a, etc.