Item Display Modes can be used to detect the display mode of an item through the item_render event, or it can be used to apply transformations to item tasks.

Item Task Exclusive

When an item task's display mode is set transformations will be applied to make the item appear as if it's rendering in that circumstance.

GUI: The transformations used by the item when being displayed in a GUI (the player's inventory for example)

GROUND: The transformations used by the item when it is dropped on the ground.

FIXED: The transformations used by the item while it is in an item frame.

NONE: Don't apply any transformations.

Universal

FIRST_PERSON_RIGHT_HAND: While in the first person right hand

FIRST_PERSON_LEFT_HAND: While in the first person left hand

THIRD_PERSON_RIGHT_HAND: While in the third person right hand

THIRD_PERSON_LEFT_HAND: While in the third person left hand

HEAD: While any item that isn't a head (player, mob, or dragon) or helmet is in your head slot.