A What's the relationship between RMS framework and the Lorentz group?

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What is the relationship between the Robertson-Mansouri-Sexl framework and the Lorentz group
The Robertson-Mansouri-Sexl framework, discussed in "Modern Tests of Lorentz Invariance", https://link.springer.com/article/10.12942/lrr-2005-5?affiliation, is "a well known kinematic test theory for parameterizing deviations from Lorentz invariance."

I'm a bit confused on the relationship between this framework, which tests experimentally for Lorentz invariance, and the group-theoretical theorems discussed in a recent thread that limit the theoretical possiblities for covariant formulations of physics, as discussed in this now-closed PF thread

https://www.physicsforums.com/threa...-postulate-or-assumption.1052965/post-6905619

in particular the (paywalled) paper "V. Berzi and V. Gorini, Reciprocity Principle and the Lorentz
Transformations, Jour. Math. Phys. 10, 1518 (1969)", https://doi.org/10.1063/1.1665000

I assume the RMS framework has some underlying group structure. The question is - is this underlying group structure the same or different than the Lorentz group? I've been perusing the Living Review article, which is rather long. Possibly it already contains the answer I seek, but I haven't been able to figure this out to my satisfaction. Unfortunately, I don't know enough group theory to answer the question myself from first principles :(.

A dumbed down version of the underlying and motivational question might be "If the Lorentz group and the Gallilean group are the only group-theoretical possibilities, what sort of test theory allows us to experimentally test for violations of Lorentz invariance?" The more specific question in the title of the thread is an attempt to answer this "fuzzier" question.
 
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