Does anybody know anything about this line?
Does this line have a name? Does this line break or comply with opening principles?

After white goes 5.d3 should black respond by defending the pawn, pin the knight on f3 with the white bishop, or just let white take the pawn on E5 with the knight?
Does this line have a name? Does this line break or comply with opening principles?
It looks like one of the variations of Ruy Lopez (Spanish Opening).

#5
It is the Ruy Lopez exchange Variation.
Yes, this line complies with opening principles.
1 e4 occupies central square e4, controls squares d5 and f5, opens the diagonal for Bf1
1...e5 black does the same
2 Nf3 develops the knight into play, controls central squares e5 and d4
2...Nc6 brings the knight into play, controls central squares e5 and d4
3 Bb5 brings the bishop into play, prepares O-O, undermines control of Nc6 over d4 and e5
3...a6 chases the bishop
4 Bxc6 gives up the bishop's pair to save a tempo and to saddle black with a doubled pawn
Black must capture 4...dxc6, as 4...bxc6 allows 5 d4. 4...dxc6 is away from the center, but opens the d-file for Qd8 and the diagonal for Bc8.
5 d3 is a less played variation: 5 O-O, 5 d4, 5 Nc3 are played more often.
5 Nxe5 does not work because of 5...Qd4 or 5...Qg5.
Rozentalis has played 5 d3 several times.
Now e5 is under attack and black must defend it in some way.
5...Bd6, 5...f6, 5...Bg4, 5...Qf6, 5...Bc5 (indirect defence: 6 Nxe5 Qd4), 5...Qd6 are all possible.
Here is an example:
https://www.chessgames.com/perl/chessgame?gid=1711849
Anything that goes up to move 6 counts as the opening, some opening lines and variations are just ways of showing how to complete an opening, while others extend into lines of play that involve the middle game.
The lines that I am focusing on stick to lines within the opening, as well as enquiring upon whether or not they break opening principles. I'm just trying to develop a simple repertoire to follow as well as learn examples of what constitutes as opening principles in order to understand them in practice.
#5
It is the Ruy Lopez exchange Variation.
Yes, this line complies with opening principles.
1 e4 occupies central square e4, controls squares d5 and f5, opens the diagonal for Bf1
1...e5 black does the same
2 Nf3 develops the knight into play, controls central squares e5 and d4
2...Nc6 brings the knight into play, controls central squares e5 and d4
3 Bb5 brings the bishop into play, prepares O-O, undermines control of Nc6 over d4 and e5
3...a6 chases the bishop
4 Bxc6 gives up the bishop's pair to save a tempo and to saddle black with a doubled pawn
Black must capture 4...dxc6, as 4...bxc6 allows 5 d4. 4...dxc6 is away from the center, but opens the d-file for Qd8 and the diagonal for Bc8.
5 d3 is a less played variation: 5 O-O, 5 d4, 5 Nc3 are played more often.
5 Nxe5 does not work because of 5...Qd4 or 5...Qg5.
Rozentalis has played 5 d3 several times.
Now e5 is under attack and black must defend it in some way.
5...Bd6, 5...f6, 5...Bg4, 5...Qf6, 5...Bc5 (indirect defence: 6 Nxe5 Qd4), 5...Qd6 are all possible.
Here is an example:
https://www.chessgames.com/perl/chessgame?gid=1711849
5Nxe5 is a standard opening variation, it does work, although black is supposed to bring out the queen as an inbetween move and recapture the pawn and possibly exchange a knight too, it is considered to be pretty aggressive and possibly on the more dynamic side, though.

“it is considered to be pretty aggressive and possibly on the more dynamic side, though.”
no, it’s just bad for white.
“it is considered to be pretty aggressive and possibly on the more dynamic side, though.”
no, it’s just bad for white.
Prove it.

-gives up the bishop pair needlessly
-white cannot castle
-black has better control of the center
+engine and this is well known