/cast fallthrough?

I'm trying to understand why the following macro works:

/cast [nochanneling] Arcane Blast
/cast [nochanneling] Arcane Missiles

Everything I read on the wiki and in the official forums says that /cast fallthrough is not possible unless the spell is off the GCD, but if you spam this macro quickly, then Arcane Missiles will cast when it procs...

What are the rules governing fallthrough? Also, is there a more complete documentation of the macro api than wowwiki/wowpedia? Any official documentation from Blizzard?

Quote:

---

Originally Posted by Chrono285

/cast [nochanneling] Arcane Blast
/cast [nochanneling] Arcane Missiles

---

Here the fix.

/castsequence [nochanneling] Arcane Blast,Arcane Blast
/cast [nochanneling] Arcane Missiles

since 4.1 its been letting you use a fall over (/cast) spells thats on cooldown with /castsequence (a bug or working as intended™) hell knows it works it works just use it like we did with click till they remove it again.