It is a standard.
Normal sensitivity is only informative, stressed sensitivity is a requirement of the standard.
Average receive power in each lane (min) is informative and not the principal indicator of signal strength. A received power below this value cannot be compliant, however a value above this does ensure compliance.
Why Stress?
Two different modules can look the same with no stress but be quite different under stress. It is important to find this difference.
Below is an example of testing two QSFP28 modules from different vendors. The first diagram shows the test without stress. The second diagram shows results of the same modules, at 70C case (stressed).
Value of Stress Testing
Qualify – pick optics with margin under stress
Verify modules work when mounted in a line card
Stress system in customer use environment to verify margin
