# Item Attribute Definitions

Group: Inventory

[Open in the interactive reference](https://docs.api.lensing.ai/lensing/v1/groups/inventoryItemAttributeDefinitions)

An item attribute definition is a descriptive property a tenant defines for itself — Colour, Size, Material — together with the values it allows.

An attribute definition names something you want to describe items by, and owns the values it permits. 'Colour' with Red, Green and Blue is one definition and three values.

This is what inventory/item-attributes assigns. An item cannot be tagged with an attribute that does not exist, so a tenant setting Everest up by API creates its attributes here first and assigns them afterwards.

valueType is TEXT or NUMBER and it is a promise about the values: a NUMBER attribute refuses a value that is not a number, because the node stores every value as text and nothing further down would notice.

Name is unique within the tenant. Creating or renaming onto a name that already exists fails with DUPLICATE_NAME rather than producing a second attribute nothing can tell apart.

Deleting an attribute that items still carry fails with IN_USE — its assignments would be left pointing at nothing. Remove those first.

## Endpoints

- [Create an item attribute](https://docs.api.lensing.ai/reference/lensing/v1/endpoints/createItemAttributeDefinition.html): `POST /inventory/item-attribute-definitions`