What is VOP in relation to Ethernet cable?

Question

Network administration

Hello.
In the settings of my cable tester there is a VOP parameter calculated as a percentage. The manual says dryly about it: "Set the Vop to be used to measure RJ45 cable"
Please tell me what this parameter means?

Answer 1

In general, colleagues suggested: "Velocity of Propagation (VOP) is the TDR measurement of the
speed of the reflected waveforms compared to the speed of light. VOP values ​​can
vary among cable types, lots, and manufacturers. In most cases, these differences are
minor and may be disregarded."