Spectral features in the cosmic ray fluxes

The cosmic ray energy distributions contain spectral features, that is narrow energy regions where the slope of the spectrum changes rapidly. The identification and study of these features is of great importance to understand the astrophysical mechanisms of acceleration and propagation that form the spectra. In first approximation a spectral feature in often described as a discontinuous change in slope, however very valuable information is also contained in its width, that is the length of the interval in logarithm of energy where the change in spectral index develops. In this work we discuss the best way to define and parametrize the width a spectral feature, and for illustration discuss some of the most prominent known structures.