Transluminal Threshold
That is the velocity a space ship must attain to make the transition from Real space into Quasi Space.
Sometimes called Slip-Speed.
With all known ISAH drive and similar Quasi space based FTL the Threshold is reached at 98.99% Light speed.
At reaching this velocity the ISAH drive activates the Quantum oscillator (the ISAH field oscillates along the three dimensions and due to the speed a new condition is created, allowing the object to traverse into Quasi Space.