The sum total of all the squares in the rectangle bounded by each L-shaped region is given in that region's red cage.
FOR EXAMPLE:
The sum of the digits in the rectangle that is bounded by R1C1 and R4C3 is written in the cage at R1C1 and R1C2.
Yellow Quinella Without a Cage
The sum of the digits in the rectangle bounded by the yellow Quinella that does not contain a cage is the same sum as that of the other yellow quinella.
Arrows
The digits along each arrow sum to the digit in its circle.