In homotopy theory, exact sequences and spectral sequences consist of groups and pointed sets, linked by actions. We prove that the theory of such exact and spectral sequences can be established in a categorical setting which is based on the existence of kernels and cokernels {\em with respect to an assigned ideal of null morphisms}, a generalisation of abelian categories and Puppe-exact categories.
Journal of Homotopy and Related Structures, Vol. 5(2010), No. 1, pp. 213-252