HeldItem
The item form of a block, under the block's own key: placing it puts the block down.
Fields
heldItem.base: string?#The vanilla item it is built on. a minecraft: item, default "minecraft:paper"
heldItem.model: string?#A model key (see content.model); omitted, the base item's own look.
heldItem.color: number?#Colour of name; only with name. 0xRRGGBB
heldItem.stack: number?#Max stack size, 1..99.