Small struct that is declared as public readonly ref struct Span<T> { private readonly ref T _pointer; private readonly

Small struct that is declared as public readonly ref struct Span<T> { private readonly ref T _pointer; private readonly int _length; ... } But the important parts are not _pointer or _length. Most of the implementation effort went into the `ref struct` part, which was released at the same time as Span<T> and is precisely what makes Span<T> powerful. It is a big thing.