It doesn't. It has ICollection<T>, which is a collection of known finite length, and IList<T>, which adds the requirement that the items can be accessed via the

It doesn't. It has ICollection<T>, which is a collection of known finite length, and IList<T>, which adds the requirement that the items can be accessed via their ordinal index, thus implicitly defining the encounter order as well. It's probably the Blub paradox speaking, but I haven't felt the need for an ISequencedCollection<T> in C#.