Items_game.txt rarities? Legendary, ancient, mythical, etc.?

[public restroom masturbator]

I was snopping through the games items_game.txt files and noticed some strange code.

Does anyone know what this is?

"rarities"
	{
		"default"
		{
			"value"		"0"
			"loc_key"		"Rarity_Default"
			"loc_key_weapon"		"Rarity_Default_Weapon"
			"color"		"desc_default"
			"drop_sound"		"EndMatch.ItemRevealRarityCommon"
		}
		"common"
		{
			"value"		"1"
			"loc_key"		"Rarity_Common"
			"loc_key_weapon"		"Rarity_Common_Weapon"
			"color"		"desc_common"
			"weight"		"10000000"
			"next_rarity"		"uncommon"
			"drop_sound"		"EndMatch.ItemRevealRarityCommon"
		}
		"uncommon"
		{
			"value"		"2"
			"loc_key"		"Rarity_Uncommon"
			"loc_key_weapon"		"Rarity_Uncommon_Weapon"
			"color"		"desc_uncommon"
			"weight"		"2000000"
			"next_rarity"		"rare"
			"drop_sound"		"EndMatch.ItemRevealRarityUncommon"
		}
		"rare"
		{
			"value"		"3"
			"loc_key"		"Rarity_Rare"
			"loc_key_weapon"		"Rarity_Rare_Weapon"
			"color"		"desc_rare"
			"weight"		"400000"
			"next_rarity"		"mythical"
			"drop_sound"		"EndMatch.ItemRevealRarityRare"
		}
		"mythical"
		{
			"value"		"4"
			"loc_key"		"Rarity_Mythical"
			"loc_key_weapon"		"Rarity_Mythical_Weapon"
			"color"		"desc_mythical"
			"weight"		"80000"
			"drop_sound"		"EndMatch.ItemRevealRarityMythical"
		}
		"legendary"
		{
			"value"		"5"
			"loc_key"		"Rarity_Legendary"
			"loc_key_weapon"		"Rarity_Legendary_Weapon"
			"color"		"desc_legendary"
			"drop_sound"		"EndMatch.ItemRevealRarityLegendary"
		}
		"ancient"
		{
			"value"		"6"
			"loc_key"		"Rarity_Ancient"
			"loc_key_weapon"		"Rarity_Ancient_Weapon"
			"color"		"desc_ancient"
			"drop_sound"		"EndMatch.ItemRevealRarityLegendary"
		}
		"immortal"
		{
			"value"		"7"
			"loc_key"		"Rarity_Immortal"
			"loc_key_weapon"		"Rarity_Immortal_Weapon"
			"color"		"desc_immortal"
			"drop_sound"		"Chicken.Death"
		}
		"unusual"
		{
			"value"		"99"
			"loc_key"		"Unusual"
			"loc_key_weapon"		"Rarity_Unusual"
			"color"		"desc_unusual"
		}
	}

[Ex Azaleane]

Probably the basic rarities used in various Source Engine games. Legendary, Ancient, Immortal and Mythical are rarities used in Dota 2 if I'm right and Unusual is used in Team Fortress 2.

[DestructionTM]

DestructionTM

[Final]

Those are all Dota 2 rarities. Unusual is a courier rarity.