How to refer objects on the stage?

I have an object created visually. How should I refer to it from classes of other objects? MovieClip(this.root).someObj or stage.someObj or MovieClip(this.root).stage.someObj? And moreover, if I want to see which frame is current on the main timeline, why I cannot just check stage.currentFrame? Why there is no such property of the s开发者_如何学编程tage, currentFrame? It has timeline, right?

root is the timeline, so MovieClip(root).someObj would do it. This should be pretty trivial to test for yourself :)