c# - Why IList<T> inherits IEnumerable<T> and IEnumerable again -

i have taken on ilist<t> , icollection<t> on msdn chance, , see definition of these 2 interfaces are:

public interface icollection<t> : ienumerable<t>, ienumerable public interface ilist<t> : icollection<t>, ienumerable<t>, ienumerable 

notice icollection<t> inherits ienumerable<t> , ienumerable, that's okay. ilist<t> inherits icollection<t>, why ilist<t> has inherit ienumerable<t> , ienumerable again?

any there reason this?

the documentation generated way can see interfaces type implements without having follow transitive links through interface inheritance hierarchy.