FlashMX: wondering what the difference is between the 3...

I have a single keyframe that I place a symbol (as graphic) in. Then under the "instance of: blahSymbol", I have a choice of LOOP, Play Once, or Single Frame.

Does it matter what I choose since this symbol (as graphic) will only exist in this one keyframe? I always leave it as Loop (default).

When would I use the other options and/or is it better to use the other options ?