In this paper, we introduce a new class of monomial ideals, called

-fixed ideals, which generalize the class of

-Borel ideals and show how some results for

-Borel ideals can be transfered to this new class. In particular, we give the form of a principal

-fixed ideal and we compute the socle of factors of this ideals. This allowed us to give a generalization of Pardue's
formula, i.e. a formula of the regularity for a principal

-fixed ideal.