  Whenever a compound exhibits a spontaneous muSR oscillation, long-range
magnetic ordering is usually inferred. Here we show that some caution is
required. The coherence length needs not to be large for a spontaneous muon
spin precession to be observed. Establishing the incommensurate nature of a
magnetic structure, solely based on muSR measurements, may not be reliable. The
absence of a spontaneous muon precession at low temperature does not mean that
the system under investigation does not display long-range magnetic ordering.
  The relaxation measured in zero and longitudinal field in the quasi-static
limit is usually analyzed in the framework of the strong-collision model, the
static polarization function being taken to be the famous Kubo-Toyabe function.
This might not be satisfactory if short-range correlation effects are strong.
Here we propose a method based on the maximum entropy concept and reverse Monte
Carlo technique which gives results consistent with those obtained in 2013 by
analytical means for the considered example.
