Finger Pointing At The Sun
You'll find that the number of times "RAW" gets invoked in a discussion about a game or a system is inversely proportional to having jurisprudence about what they're talking about. The usual dichotomy is that there's "RAW" / "Rules As Written", vs "Rules As Intended". In practice what this means is there's whatever the rules are saying according to the beholder and that is put up against, simultaneously:
- What the author said they meant for it to do (which at best agrees with the beholder's reading and at worst is no longer the rules as written)
- Literal readings from others (they necessarily don't get to be RAW according to the beholder if they aren't the same conclusions the beholder reached)
- What jurisprudence says you do with a rule... <- the big enchilada
From my perspective, once a rule is written it has to be read, and the most you can do there is have read it differently from someone else. I would put forward that there is not really a meaningful difference between RAW and RAI. The difference comes down to what rules were provided in the book, and what was provided elsewhere. The author, the beholder, and the other might all disagree about what the written rules indicate but fundamentally they're all working off the same page. Whatever they do with that, is playing it rules as written. It does not matter that the game plays differently at different tables, it really doesn't.
The opposite of rules as provided then would be the house rules and the errata. An erratum (in ttrpg parlance anyways) is really a rule that was provided late, it was the author saying "ahh i fucked up, what I meant was", the author saying "Actually, those two words should be swapped", the author saying "well... it's intended to do X effect, not Y." Sometimes, the nature of these errata are informal descriptions and not formal editions to swap text around. Errata are closer to the rules as provided, compared to house rules.
A house rule is just a rule change made deliberately. You have to assume some good faith, some things are rulings and not a house rule. Things are not house rules just because you don't think the rules as provided allows for them. A house rule posits like "I always give Paladins a starting warhorse," a ruling reasons something like "Paladins have orders that will loan them a warhorse in my game, so you can get one to start with." Same difference, one of them was just done deliberately and the other was inferred without a deliberate rules change.
Jurisprudence
This comes up a lot, all the time, in just about every rpg ever. How do you determine that someone is reading a rule... in bad faith? How do you really peg someone as a rules lawyer? What DO you do, when hit with the rock solid argument "it doesn't say that a dog can't play baseball"?
The entirety of the player's handbook and dungeon master's guide, the core book, the characters and campaign books, the source book, are fingers pointing at something they want you to see. Once you read and absorb that text, you get a sense of what they are trying to indicate. Yes, it says roll this die and read this result to mean this outcome here. Yes, it says these items cost this much and those rented helpers cost that much.
Once you absorb a book, and play a game, and keep making rulings, keep re-reading the rules, keep playing the game, and talk with others about the game, something happens: you either start to get a sense of the game beyond the rules or you don't. Presume for the sake of argument that you do: you'll find rules worded inconsistently (implying you know how they should have been worded), you'll make rulings that look like house rules the way they seem to posit so much, and you'll come to the point where rather than following the rules as they apparently command you to, you'll be using the rules just for their utility in making the game you want to play come together.
In conclusion
This was inspired by seeing someone talk about how a rulebook "permitted" them to modify something. The concept was really intriguing; was the rulebook the "authority" at the table? This bicameral mind type of gamemaster is sadly not that rare. There is no such thing as jurisprudence in their mind because to them they're just playing the game rules as written. When the guy doing the interpretation doesn't even realize they're responsible for interpreting it, you better hope the book tells them dogs can't play baseball -- and that they know what the words "baseball" "play" and "dog" are without a glossary of terms.