(p. 10) The content/expression distinction, and anything like it, is notably absent in the architecture and knowledge representations of computer systems that generate narrative, as is discussed in the next chapter.
When studying non-interactive story, the separation of content and expression is relatively uncomplicated; there is a full “world” going on, and the expression of it are those parts the author chooses to portray. Interactive story adds the complexity of code: there is something genuine and tangible in the content layer, besides it merely being in the author’s head.
(p. 13) Interactive fiction produces texts that describe characters and objects even when these characters and objects are not simulated, that is, when they do not have a representation in the world model.
In terms of a general theory, there’s something more like three layers:
* the expression layer
* the content layer of things with code behind them; e.g. characters with an object in the world model the player can interact with
* the content layer of things without code; e.g. characters mentioned in passing but only included in text, and with no chance of interaction. This can have sort of a halfway status when referring to groups of things. In a crowd scene, for example, there may be text messages referring to individual people doing things (“a lady near the front checks her cell phone”) while the code may only allow reference to “the crowd”.
There’s also what one might refer to as “second-order content” — when examining an object, there tend to be details, and if one can examine those details that’s a second level. Those details may themselves have details that can be examined. At some level this recursion has to stop, either through a description which suggests no further object (“it is blue”), subsuming the detail as part of the object description (so the ornate wheel on a bicycle is considered in the world model identical to the bicycle) or leaving the detail as expression-but-not-content.
(I believe Andrew Plotkin coined the second-order terminology, but I haven’t been able to find where. Anyone with a link?)
(EDIT: Thanks to Dan Shiovitz for tracking down who coined the second-order terminology: Paul O’Brian in a review of Out of the Study.)
(EDIT EDIT: Emily Short has found the reference even earlier in another Paul O’Brian review of Hunter in Darkness. Is there one even earlier? I had previously thought it came up in regards to The Light: Shelby’s Addendum.)
(p. 14) But when attempting to automatically produce narrative variation, it makes sense to consider only those existents and entities that are explicitly represented in software . . .
The nn system goes by the precept “every piece of expression has a piece of content in the world model behind it”. This allows the system to have complete control over the text and to modify any part. (To give an example of system control, the classic Inform library hard-coded “you” in its responses, whereas Hugo allowed for changing between first/second/third perspective with a single variable.)
(p. 14) The IF system developed will be, when released, the first system to allow authors to easily manipulate the telling of their worlds, allowing a number of literary techniques to be integrated into IF.
To be more specific here, the system allows a number of literary techniques to be integrated within the system automatically, as a system of coded rules just like the world model.
This will allow, for example, the actions of multiple NPCs to be printed in different ways or out of order. Perhaps the player is “following” one character, whose actions are provided in detail, while any other characters passed by are described with much terser prose.
This is of course achievable with current systems, but the goal here is to elaborate automatic narrative variation beyond what an author would normally attempt manually.