  It is shown that the reflection 2Cat --> 2Preord of the category of all
2-categories into the category of 2-preorders determines a monotone-light
factorization system on 2Cat and that the light morphisms are precisely the
2-functors faithful on 2-cells with respect to the vertical structure. In order
to achieve such result it was also proved that the reflection 2Cat --> 2Preord
has stable units, a stronger condition than admissibility in categorical Galois
theory, and that 2-functors surjective both on horizontally composable triples
of vertically composable pairs and on vertically composable triples of
horizontally composable pairs of 2-cells are effective descent morphisms in
2Cat.
