Theoretical analysis reveals that ordered functions play an important role in the running and dynamical behavior of networks.Post function class has been known as the maximal ordered function.However

it only describes the positive regulatory mechanism appeared in genetic regulatory networks.In this paper

we extend the Post function class so that it contains both the positive and negative regulatory mechanism.Simulation results show that the extended Post function class can present similar dynamical characters as the original Post class and Canalizing function class.It has the ability to keep ordered behaviors and can emerge the long-range correlated dynamics.From the point of view of natural evolution

we conclude that such abundant ordered functions are more possible to be selected as the interactions among genes.Finally

the distribution of function classes on eight real systems also partially supports our conclusion.