AD7667 input question

hi all:

      Looking at the AD7667 datasheet, I have troubles understanding Figure 45. Using the AD7667 in 16-Bit Bipolar and/or Wider Input Ranges.

Why the op amp can convert  ±10V to 0-2.5V. Should U2 connect the analog input signal to R2 and R3? But the gain is not right.

thanks