The concept of Large signal voltage gain 's measurement condition ?


I would like to know how to decide the condition of "Large signal voltage gain".

For example, AD8542's condition is

Vs=2.7V VCM=1.35V

    RL=100Kohm Vo=0.5 to 2.2V

Vs=5V VCM=2.5V

    RL=100Kohm Vo=0.5 to 2.2V

How to decide this vo condition?

Why 0.5?   Why 2.2V?

Other case,  OP295's condition is

Vs=5V VCM=2.5V

   RL=10Kohm  0.005V<= Vout <= 4.0V


     RL=10Kohm    no output voltage description.

in this case why 0.005V?  Why 4.0V?

In AD8542 case, Vs=5.0V, 3.0V's vo conditions are same as Vs=2.7V.
It means to cut the test ?  and Avo does not depend on Vs voltage?

For example, condition is Vo= 0.1V to 2.5V,then how much the Avo will degrade?

In OP295's case, why vo is very low?

I would like to know the concept of vo decision.