With apologies for a potential thread derail...
From Mike Mearls
The Forge might be useful. It's the sort of thing that you have to go look at and judge for yourself. I find it a bit too steeped in jargon, but a lot of the end ideas are useful to think about in terms of my work.
I think this quote neatly sums up my attitude to The Forge. I find it interesting that people have deconstructed RPGs in such an academic manner--the hobby/industry has "grown up" if you will--but it's tangential to the vast majority of people's experience, much as how people can enjoy Jane Austin without a degree in English Literature. Its terminology is arguably helpful in discussions such as this but, unlike in academic discourse, the jargon is not ubiquitous.
"Author stance", at least as I use it (from The Forge) refers to choosing actions for one's PC from the point of view of an author - ie "It would be pretty cool for my guy to do this awesome thing" - rather than from the point of view of the character him-/herself. In some playstyles, author stance then involves writing in a rationalising in-character motivation (eg "My guy loves to show off!").
I still regard them both as director stance - in both cases the player is doing something other than stipulate a choice/action for his/her PC.
Author stance, at least as The Forge uses that term, is not about scope of player control over gameworld. It's about reasons for declaring PC actions. If those reasons are derived from in-fiction considerations ("My guy wouldn't do that") you're in actor stance. If those reasons are derived from real-world considerations ("I want to play a guy who wouldn't do that") you're in author stance.
Yes, this is my interpretation of Author stance too. I wonder if "Author" is perhaps an inaccurate term--but that is a discussion for another thread!
Author stance is assumed when the person playing a character determines the character's decisions and actions on a basis not solely borne of the character's priorities. Generally, the actual player's priorities have primacy here and are independent of the character's current, pre-established knowledge and perceptions. You're most often establishing backstory for your character, leveraging it immediately and using it as a means to an end; that end may be "the rule of cool", "genre proliferation", or merely "flavor/color of mechanical resolution of a conflict".
Whilst I agree with the first part of this I'm not so sure about the part I've emphasised, although that may just be a difference in perspective.
I believe it's possible to draw a (very loose) comparison between Actor stance and Method Acting: the player strives to remain in character throughout, using only in-character knowledge and psychological motivation to dictate the PC's actions.
In contrast, Pawn stance views the character sheet as little more than a player token in Monopoly: it is the means by which the player interacts with the game environment, with no regard to the motivation of the character itself. "Character" here is somewhat of a misnomer.
Author stance stands somewhere between the two. It is similar to Actor stance in that the psychological motivation of the character is often important to the player but this motivation is modified, possibly retroactively, by the metagame considerations of the player. Author stance is similar to Pawn stance in that the character is often a means to an end for the player to interact with the game environment (by doing "cool stuff") irrespective of what "the character" would be motivated to do in that situation. The Forge clearly distinguishes between Actor and Author stance and places Pawn stance as a subset of Author stance. As [MENTION=42582]pemerton[/MENTION] suggests, the line is somewhat fuzzy in practicality if not in definition.
I don't think any of these three stances (Actor, Author and Pawn) have the "authority" to dictate the relationship between the PC and the guard. However, a successful skill check (for example) could be rationalised and explained in-fiction as such.
That's my take on things, at any rate
