picture this 3 person lineout...




X    X X X
      X

               X
                    X
X              X         X
                    X        X 
                         X
           X                 X



the 3 people are pretty athletic. they have a series of plays designed
to attack at the throwin. should the opposing team drop their forwards
directly behind lineout you also have a pure possession throwin play. 
the usual short lineout kinda thing. the idea in that case is to go
directly to backline immediately. because you have a 4 person overload
or close to that. 

if other teams marks your backline attack hard in throwin lane region of
field. the people stacked behind your backs are you big folks.
props etc. the object is for them to have the ball when the opposing
team stops you. in other words they need to burst onto ball and take it
into tackle. these folks should be able to secure ball for you. 

you can do quite a few different moves off this backline formation. 
there are more options than the normal backline. more later.

in the normal full lineout you essentially narrow the field by 15+
yards for the defense. you only actually attack on the remaining part. 
the idea behind this lineout allows you to use entire field to attack. 
puts more pressure on defense. you also are attacking upfield right
off the throwin. puts pressure on the defending team from the
very beginning of lineout. they also will at some points of attack
have to defend your quick folks with their slow ones.

lets say you get the ball and attack at throwin. you get maybe 5-10
meters up field. at that point you set maul/ruck and swing ball out to
backline thats already there in stacked formation. then the folks that
were in ruck run back and form a backline on that side. your scrumhalf
is still following ball around as per usual but the folks in the ruck
arent chasing the ball. you already have your props etc. stacked in
backline. you already have backline to wide side of field. you have
split backs immediately. 

the backline plays to run out of this formation are too numerous
to cover them all. switches and crashes have potential to be very
deceptive. 

the stacked aligment is the most basic. 

another option is:


X   X X X
     X

                X
             X     X       X
X               X       X     X
                           X

        X


same thing really just the backline moves start differently. would put
slower and/or more powerful folks at left and right side fo diamonds
put folks that have speed and/or pick holes well at back of diamond
put flyhalf ball handling types at front of diamond. 

another option is:


X   X X X
     X

                X

                X           X
             X     X
                            X
X                        X     X 


slower and/or more powerful folks directly behind the two flyhalf types.
they would take the ball into congested traffic. quicker folks to the
sides behind them. probably helpful to look at the american football
wishbone offense for various play selections plus the added options 
from integrating with the second group in backline.