为什么母版页在ASP.NET中没有PreInit事件？

以下是主页与内容页合并时发生事件的顺序:

Content page PreInit event.
Master page controls Init event.
Content controls Init event.
Master page Init event.
Content page Init event.
Content page Load event.
Master page Load event.
Master page controls Load event.
Content page controls Load event.
Content page PreRender event.
Master page PreRender event.
Master page controls PreRender event.
Content page controls PreRender event.
Master page controls Unload event.
Content page controls Unload event.
Master page Unload event.
Content page Unload event.

但为什么母版页没有PreInit活动ASP.NET？