AD7738 Zero and Full scale System Calibration

AD7738 circuit details:

REFIN+ and AINCOM connected to 2.5V reference, REFIN- connected to ground.

Analog input voltage ranges selected as +/- 1.25V.

MUXOUT+=ADCIN+ and MUXOUT-=ADCIN-

AVDD connected to 5V

What is the range (min and max) of external voltage that can be connected to perform

  1. Zero scale System calibration
  2. Full scale System Calibration