It is not expected that you will fill every slot for a custom song. The pack works fine with as few songs as you want to add!

If no custom songs have been added for a location, no music will play there.

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Creative/Menu:

Overworld songs, including universal and biome-specific songs, can play in Creative Mode or in the main menu. Only Deep Dark songs are excluded.

custom1-custom60

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Overworld (Universal):

These songs play everywhere in the Overworld, regardless of biome, except when underwater and in the Deep Dark.

These songs are weighted lower than biome-specific songs, so there is an equal chance to hear universal or biome-specific music in each biome.

custom1-custom10

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Overworld (Non-Biome Specific):

These songs play in any biome not covered by a biome-specific playlist, such as Plains and Savannas.

custom11-custom20

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Underwater:

These songs play when the player is underwater.

custom21-custom25

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Forest:

These songs play in the Forests, Birch Forests, and Roofed Forests.

custom26-30

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Calm Forest:

These songs play in Flower Forests, Cherry Groves, and Old Growth Taigas.

custom31-35

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Humid Forest:

These songs play in Jungles and Swamps.

custom36-40

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Desert:

These songs play in Deserts and Badlands.

custom41-45

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Mountain:

These songs play in Snowy Slopes, Meadows, Groves, and all Peaks.

custom46-50

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Lush Caves:

These songs play in Lush Caves.

custom51-55

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Dripstone Caves:

These songs play in Dripstone Caves.

custom56-60

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Deep Dark:

These songs play in the Deep Dark. This is the only biome where music does not play constantly. Universal Overworld music does not play here, either.

custom61-65

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Nether (Universal):

These songs play everywhere in the Nether, regardless of biome.

custom66-custom70

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Nether Wastes:

These songs play only in the Nether Wastes. 

custom71-72

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Crimson Forest

These songs play only in the Crimson Forest.

custom73-74

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Warped Forest

These songs play only in the Warped Forest. 

custom75-76

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Soul Sand Valley:

These songs play only in the Soul Sand Valley. 

custom77-78

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Basalt Deltas:

These songs play only in the Nether Wastes. 

custom79-80

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The End:

These songs play once the Ender Dragon is defeated.

custom81-85

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The Ender Dragon:

These songs play only while the Ender Dragon is alive.

custom86-89

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Credits:

This song plays over the End Poem and credits.

custom100

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Reserved:

These songs are reserved for future updates. For now, they are treated as universal End music.

custom90-99

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