The setting up of an observer chorus requires a protocol, that is, a careful definition and preparation of the elements of the chorus before any information is collected. A protocol will involve a number of requirements.
A specification of the spacetime geometry of the flux of worldlines in a chorus is fundamental to the physics being reported. For example, the worldline flux of an inertial frame chorus will be very different to that of a laboratory undergoing acceleration. This can have a significant impact on the nature of the observations, as the Unruh effect demonstrates [Unruh, 1976]. According to that effect, a particle detector accelerating in apparently empty spacetime is predicted to detect a thermal spectrum of particles.
All members of an observer chorus should have an agreed standard of measurement. If this is not done carefully, disasters can occur. A notable example is the failed Mars Climate Orbiter disaster in 1999. This occurred because information being processed on Earth was assumed to be in Imperial units (pounds, etc.) whilst the same information being processed by the orbiter itself was assumed to be in Standard International units (kilograms, etc.).