I "draw the line" around the shared fiction.
I guess people can try and incorporate by reference -
the whole of that tome's content is part of our shared fiction - but in practice that won't work, because not everyone can hold the whole of the tome in their head at once. So what people actually agree on will prevail over what is in the tome, where the two come apart. This can cause issues in games that aspire to adhere to some prior canon - it's necessary to make notes about the game's departure from the canon, or perhaps down the track for everyone to agree to change their mind about what happened in the shared fiction.
Yes. This would be the use of a cue. I mean, it's not as if Vincent Baker hadn't noticed this
back in 2003:
What has to happen before the group agrees that, indeed, an orc jumps out of the underbrush? . . .
sometimes, lots of mechanics and negotiation. Debate the likelihood of a lone orc in the underbrush way out here, make a having-an-orc-show-up roll, a having-an-orc-hide-in-the-underbrush roll, a having-the-orc-jump-out roll, argue about the modifiers for each of the rolls, get into a philosophical thing about the rules' modeling of orc-jump-out likelihood... all to establish one little thing.
If a table is being used as a mechanic "to ease and constrain real-world social negotiation between the players at the table", then we would expect that referring to it makes a difference to what is said next. Otherwise it would be a failed mechanic!
I don't even know what the question is!
We can draw technical distinctions here, if you like.
For instance, the shared fiction is - in some sense -
asserted jointly by the game participants. (Though the assertion is in some sort of fictional rather than doxastic mode.)
Whereas an entry on a table is not asserted. It is presented by its author as mere possibility.
And while a tome of lore
is asserted by its author (again, in some sort of fictional mode), that assertion is
not part of any other table's shared fiction. If you like, we could index the fictions and say that the tome of law is asserted as a component of fiction L (the tome-author's fiction) but not as a component of fiction T (the table's shared fiction). Only when some gameplay procedure leads the table to consult a cue and adjust its fiction in response - including, say, by reiterating something from fiction L within the context of fiction T - does it become part of the shared fiction.
To follow on from my preceding paragraph, one doesn't make a cue part of the fiction. I mean, there's no harm in speaking in that way as a matter of casual description, but it won't do for technical analysis.
The assertion found in the cue is asserted as a component of fiction L. The assertion found in gameplay is asserted as a component of fiction T. The two assertions may be the same item at a certain level of linguistic abstraction (eg they are lexically and syntactically identical), but they are not the same item considered as speech acts, in part because they are indexed to different fictions. Failure to notice that point causes needless confusion - eg it causes confusion in explaining how I can run a Greyhawk game, and you can run a Greyhawk game, yet not everything in your table's fiction is part of my table's fiction, and not even everything in Gygax's gazetteer is part of my table's fiction. Whereas maintaining a clear sense of what fiction we are indexing some particular fictional-mode-assertion to makes this fairly easy - and to say that I am running a Greyhawk game is not to say anything, directly, about the content of my table's fiction; but rather is to say something directly about what is included in my cues, which might then suggested some further (defeasible) inferences about what my table's fiction might include.
I assume that your word "feasible" is meant to be an instance of the sort of normativity you refer to? I think the use of "normative" here has the potential to be misleading, because all fiction and indeed probably all speech is normative in that sense (maybe absurdist literature is an exception?) and so it doesn't point to any distinctive feature of RPGing.
Likewise the implied elements. If I go into my kitchen and reach for a mixing bowl, then - everything else being equal - that implies the possibility of a cake or some other prepared food item. If I pick up some dice and start shaking them, then - everything else being equal - that implies the possibility of generating a random number and paying some attention to it in my ensuing activity. And if I identify a particular thing - say, a character sheet - as a cue for my RPGing, then that implies the possibility of drawing on that cue in the course of my RPGing.
These are just ordinary features of deliberate human behaviour, aren't they?
I assume that "signifier" as used in narratology comes from Sausurrian linguistics. It means something like "meaning-bearing item". What is useful about the terminology of
cues, in my view, is that it enables us to achieve more precision in our consideration of the sorts of meaning-bearing items that figure in RPG play, and also of the
way in which they bear meaning and contribute to the activity.