Easy Question For Ya

I dont get what onClipEvent (load) and onClipEvent (enterFrame) mean or do…i think that it means when the movie reaches here in the time line do this…like when the movie has loaded "onClipEvent (load) " do this (whatever you want a do)…or when the movie reaches this frame “onClipEvent (enterFrame)”

but you can just put a do this command in on that frame, you dont need to tell it to wait to get to the frame…you dont have to tell the movie clip “on load” (wait till your loaded) the do some thing…you just put the do something on frame one…im starting to over complicate thing i feel…just if someone could clear this up for me id be a happy man…whats onclipevent do