When you go to buy something in a convenience store you can be reasonably certain of what’s going to happen in that situation. First, you’ll walk in and you might say ‘hello’. Then you’ll ask for some batteries and then pay. We can guess this sequence due to our previous experience with these kinds of situations and the fact that they are nearly always the same. Some parts may change (you might not say hello) but you always have to pay.
Within certain recurring sets of texts then, coherence of structure is formed through obligatory and optional elements, the totality of which forms the Generic Structure Potential (GSP) (Halliday & Hasan, 1985) for that set. For example, the GSP for ‘service encounters‘, is:
In other words, there are certain obligatory elements that characterize the genre, in this case the ‘Sale’, ‘Purchase’ and ‘Purchase Closure’, and other optional ones that add elaboration but are not necessary. There is thus a ‘structure’ to social interactions. We can call it ‘Potential’ because it has a predictive quality that allows us to navigate these social situations almost unconsciously.