Motivated by real data sets, that does not fit one of the parametric distributions, many well-known non-parametric families of life distributions have been defined and all their properties are explored. In particular their convolution (adding life of independent components), closure formation of systems of n independent components (parallel systems, series system, k-out-of n systems), and mixtures of these life lengths conditioned on different processing (working) environments, are established. However, the researcher, and after surveying the available non-parametric families, has realized...