When you browse the MPQs, you will find a lot of different names for creeps and units that got changed throughout the game design process.
There's actually a lot of "old stuff" that simply got removed from the game hidden in the existing JASS natives.
For example, in addition to DAMAGE_TYPE and ATTACK_TYPE for the native that deals damage, there also is WEAPON_TYPE, which does absolutely nothing, as there is only one to use there: WEAPON_TYPE_UNKNOWN.
Also, btw, the DAMAGE_TYPE constants available hint that at some point in the design process, there was actual elemental damage in the game. While DAMAGE_TYPE works and returns event responses on damage events, none of the abilities in the game actually deal elemental damage. The game only destinguishes between physical and non-physical damage (for items like the rune bracers).
So the orb of fire does not actually add fire damage. It just adds attack power. I guess this got changed throughout the design process for simplification of gameplay. My guess is that they initially planned elemental resistances.
I guess this is a relic from before the game constant based armor system as we know it got implemented.
Then, there are some things like MIDI file support, that never actually made its way into WC3. You can use it by enabling local file support and importing a certain dll into the map script.