Reading a tabletop roleplaying game document, there might be tables and charts of possibilities -- anchors that give you space to imagine a world between them. Maybe writing is not so different from this after all, just less explicit about it.
If I write the simple sentence, Don't breathe that stuff, it leaves open so many little questions which might be inconsequential to the plot but beautifully consequential to the experience of inhabiting the world...
Every statement has negative space, but so as to be able to tie it better to A Pattern Language, I'll call it space 'outside' the explicit, instead. 'Outdoor' space.