Minecraft wiki entry for Firework_Rocket, associated text: Entity data
Tags common to all entities[show]
Tags common to all projectiles[show]
 FireworksItem: The crafted firework rocket.
 Count: The item count, typically 1.
 id: The id of the item, should be minecraft:firework_rocket.
 tag: The tag tag.
 Fireworks: One of these may appear on a firework rocket.
 Explosions: List of compounds representing each explosion this firework causes.
: A firework explosion.
Tags common to all firework explosion effects[show]
 Flight: Indicates the flight duration of the firework (equals the amount of gunpowder used in crafting the rocket). Can be anything from -128 to 127.
 Life: The number of ticks this fireworks rocket has been flying for.
 LifeTime: The number of ticks before this fireworks rocket explodes. This value is randomized when the firework is launched: ((Flight + 1) * 10 + random(0 to 5) + random(0 to 6))
 ShotAtAngle: 1 or 0 (true/false) - true if this firework was shot from a crossbow or dispenser.