I was doing that elimination style because I was extremely stuck.

You know how you have a box that can be 1 of 2 answers, you "hypotheticallu" fill out a blank sheet to see what other boxes would be, if that box was option 1 or option 2, then you go through it looking for any boxes that share the exact same answer, whether it is option 1 or option 2. I call it elimination.

Well I think I discovered a new use for it. I was doing that method I just talked about, where I was filling it out, but I didn't get any matches. However, I had a 2AC option at bottom of a row (I am was doing Super Sudoku when I found this method), I was doing one of those option 1 or 2, and when I filled it out on separate paper, that 2AC box, had "2" for option 1, and "2A" for option 2.

I didn't solve it, but I realized that either way it can't be C! I don't know what method this is called, and I am sure this is a real thing, because I started doing the method in other hard sudkous and it always worked. I have a question about it.

1-What are these methods called? Because I have done like dozen of these, and seriously every time I get something like 2A or A for a 2AC box, like mentioned above, and I can always cross out the C. But I have a big question about this. In this same type of example, 100% of the time (as far as I have noticed since using it) the final answer always ends up being "A", aka the answer ends up being the one that is in the box for both option 1 and option 2. Like in another sudoku, I had a 3AB box, where I use my elimination from another box and either way this 3AB box ends up being 3 or 3B, which of course I can cross out A, but the final answer is 3, just like 2 was the answer for 2 or 2A.

However, I know this can be complete coincidence, but I am hoping this is a method, especially that one I just mentioned, I just haven't came across a sudoku where that didn't work. Like I have yet come across a box that is either 9 or 92, and it ends up being 2. It is always 9. I might come across one, but I am thinking this is a method.

Looking at a technique page online, the method I call "elimination", is called "forcing chains" according to another website. I am just wondering if the other uses of the method are called something different or just something you can do as part of it, but I am very interested if my theory of 92 or 2, theory is right, where the answer will always be the one that is on both option 1 and option 2.