UNIT_SPELLCAST_SUCCEEDED and multiple results

[doofus]

I am using UNIT_SPELLCAST_SUCCEEDED to detect the spells that the player casts. I am not using the combat log.

I have noticed when I cast a spell, eg Frostbolt I receive two events, one when the spellcast is complete with event id 116, and another event when the spell hits with event id 228597. I presume this is for spells that can miss/resisted? Other spells, like Ice Lance only produce one and only event, as you'd expect.

If the second event is to notify me of a successful hit/miss/resisted and also of the travel time associated with some spells, then why do we not have a completely different event like "SPELL_HIT_MISS" or something similar?

How can an addon tell which events are the actual spell cast, and which are the result which due to travel time and due to hit/miss can have varying results?