  Some reasons are given to suggest that the interpretation of the Lorentz'
transformations as if they referred to coordinates instead of to intervals
could be incorrect. Besides, the usual form of such transformations, by using
variables that represent finite values instead of differentials, could be
another error. Later it is shown that the Lorentz contraction factor must not
have the form currently accepted for it if the Lorentz contraction factor is
assumed to be equal to the quotient between time differentials.
