Can someone explain me what the "full line-out" rule in rugby is?
No. 2 is throwing in, or standing around, but not involved in the line out.
The other forwards do not usually line up in that position, it was just to show the numbers in the line out.
For the Additional Details, (I will leave the first response.)
In short, if you kick the ball whilst inside your 22, and the ball goes directly into touch, the line out occurs where the ball crossed the side line, whereas, kicking the ball directly into touch, whilst outside your 22, the line is taken from the position you kicked the ball.
I think this was originally done to give more advantage to the defending team. It would be / is / was easy to have a line out in the opposing 22 and score a try.
The definition of kicked directly into touch is:
"‘Kicked directly into touch’ means that the ball was kicked into touch without landing on the playing area, and without touching a player or the referee." , (Law 19 Touch and Lineout ), 
The definition of the 22 is:
"‘The 22’ is the area between the goal line and the 22-metre line, including the 22-metre line but excluding the goal line." , (Law 1 The Ground, and Law 19 Touch and Lineout ), 
Law 19.1 "THROW IN", explains when and where you gain ground from kicking the ball directly into touch.
"NO GAIN IN GROUND", explains about when the line out is brought back to where the person kicked the ball. , 
"GAIN IN GROUND", explains when the line out is taken where the ball went into touch.
It even has a picture to show different positions of receiving the ball, and being able to kick directly into touch.
To provide some help, if you are looking at grabbing the laws seperately, here is the current list of laws, so you do not have to open each one up to see what it relates to.
"BEFORE THE MATCH
"Law 1 The Ground
"Law 2 The Ball
"Law 3 Number of Players - The Team
"Law 4 Players’ Clothing
"Law 5 Time
"Law 6 Match Officials"  p. ii
"DURING THE MATCH
"Method of Playing the Match
"Law 7 Mode of Play
"Law 8 Advantage
"Law 9 Method of Scoring
"Law 10 Foul Play
"Law 11 Offside and Onside in General Play
"Law 12 Knock on or Throw forward"  p. ii
"In the Field of play
"Law 13 Kick off and Restart Kicks
"Law 14 Ball on the Ground - No Tackle
"Law 15 Tackle: Ball carrier Brought to the Ground
"Law 16 Ruck
"Law 17 Maul
"Law 18 Mark"  p. ii
"Law 19 Touch and Lineout
"Law 20 Scrum
"Law 21 Penalty and Free Kicks"  p. iii
"Law 22 In-goal"  p. iii
So to answer your question there is not really a full line-out rule. All the line-out rules are the same
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