When the measurement mode is 20 k and the gauge method is 4 gauge, the range is －5000 µε to +5000 µε(microstrain), but I can measure up to ±20000 µε. What is the accuracy?

The range of the strain input module depends on the measurement mode and gauge method. (see the table below)

Even if you select the 2 gauge or 4 gauge method, 1 gauge method measurement is still possible, and rangeovers and other errors will not occur. However, the accuracies are only guaranteed within the ranges of each gauge method.