Paralorentz transformations

In special relativity, events that are simultaneous in one inertial reference frame (IRF) are not so in another. 75 years ago L. I. Mandelstam showed that absolute simultaneity of events in different IRFs is achieved by using infinitely fast signals instead of light to synchronize clocks. 25 years later F. R. Tangherlini showed in an independent study how spatial coordinates and time will in this situation transform on transition from one IRF to another. Although different IRFs are on different footing in this case (the frame with the observer being the privileged one), the Tangherlini transformations are still capable of describing the known experiments testing special relativity.