> ## Documentation Index > Fetch the complete documentation index at: https://docs.joinluminous.com/llms.txt > Use this file to discover all available pages before exploring further. # Set base UOM for a unit class > Mark a UOM as the base unit for its parent unit class. The previous base UOM (if any) is unset, and conversion factors continue to be expressed relative to the new base. ## OpenAPI ````yaml /api-reference/build.yaml post /unit-classes/{unitClassId}/default-unit-of-measure/{unitOfMeasureId} openapi: 3.0.0 info: title: Luminous API version: 1.0.0 description: API documentation for Luminous servers: - url: https://{companyName}.api.joinluminous.com/external/api/v1 variables: companyName: default: companyName description: Your company-specific subdomain security: [] tags: - name: Products description: Get and manage products - name: Pricing description: Manage price schedules, levels, and customizations - name: BOMs description: Manage Bills of Materials (BOMs) - name: Labels description: Label rendering via Labelary ZPL service - name: Companies description: Manage business accounts and their associated data - name: Contacts description: Manage contact information for individuals - name: Suppliers description: Manage suppliers (factories) — vendors used on purchase orders - name: Supplier SKUs description: Manage per-supplier SKU and unit-cost overrides for products - name: Locations description: Manage warehouses and locations - name: Inventory description: Get and adjust product stock levels - name: Lots description: Create, update, and delete product lots (batches) - name: Transfer Orders description: Manage transfer orders - name: Fulfillment Orders description: Manage fulfillment orders and picklists - name: Purchase Orders description: Get and modify purchase orders - name: Receiving Reports description: Manage receiving reports - name: Payment Obligations description: Manage payment obligations for purchase orders - name: Sales Orders description: Manage sales orders and sales order shipments - name: Purgatory description: >- Inspect and resolve non-posted sales orders in the purgatory staging workflow - name: PickFlow Shipping description: >- Provider-agnostic shipping rates, services, packages, and label purchase for PickFlow - name: Cycle Counts description: >- Create, drive, and post PickFlow cycle counts — batches, per-warehouse sessions, and CSV import/export - name: Print Stations description: List paired print stations and enqueue print jobs to them - name: Invoices description: Get and manage invoices - name: Work Orders description: >- Manage work orders — production lifecycle, steps, materials, links, shipments, and comments - name: Production Batches description: Group and manage work orders as production batches - name: Bills description: >- Accounts payable bill management, payments, attachments, allocations, and variance - name: Prepayments description: Manage vendor prepayments and applications - name: Vendor Credits description: Manage vendor credits and applications - name: Vendor Returns description: Manage vendor returns and credit generation - name: Customer Returns description: Manage customer returns (sales returns), receiving, and restock behavior - name: Stock Snapshot description: Point-in-time stock snapshots with export support - name: Consumption description: Consumption reports and exports - name: Inventory Aging description: Cost-layer-based inventory aging reports - name: Bills Reports description: Accounts payable bills aging reports - name: Forecast description: Materialized forecast data - name: Reports description: Close the books, inventory discrepancy, transaction COGS, and EDI reports - name: Tags description: Add/remove tags across various resources - name: Custom Fields description: Get and set custom fields across various resources - name: Currency description: Currency configuration, exchange rates, and conversion - name: Integration Mappings description: Manage integration mappings for external systems - name: Integration Field Mappings description: Manage field-level mappings between Luminous and external systems paths: /unit-classes/{unitClassId}/default-unit-of-measure/{unitOfMeasureId}: post: tags: - Units of Measure summary: Set base UOM for a unit class description: > Mark a UOM as the base unit for its parent unit class. The previous base UOM (if any) is unset, and conversion factors continue to be expressed relative to the new base. operationId: setUnitClassDefaultUom parameters: - in: path name: unitClassId required: true schema: type: integer description: Unit class ID - in: path name: unitOfMeasureId required: true schema: type: integer description: ID of the UOM to mark as base responses: '200': description: Base UOM updated content: application/json: schema: type: object properties: data: type: object description: >- A grouping of related units of measure (e.g. "Length", "Weight"). Each class may have a base unit and a list of UOMs. properties: id: type: integer created_at: type: string format: date-time updated_at: type: string format: date-time status: type: string nullable: true name: type: string base_class: type: boolean description: True for the system base class (read-only). unit_of_measures: type: array description: Present when the relation is loaded. items: type: object description: >- A single unit of measure (e.g. "Pound", "Kilogram") belonging to a unit class. properties: id: type: integer created_at: type: string format: date-time updated_at: type: string format: date-time status: type: string nullable: true unit_class_id: type: integer unit_class: type: object description: Present when the relation is loaded. nullable: true properties: id: type: integer name: type: string base_class: type: boolean name: type: string description: type: string nullable: true base_unit: type: boolean description: True if this UOM is the base unit for its class. unit_conversion_rules: type: array description: Present when the relation is loaded. items: type: object description: > A rule converting from one unit of measure to another. `type=SYSTEM` rules apply globally for a class (e.g. 1 lb = 0.453592 kg). `type=SKU` rules override system rules for a specific product (`product_id`). properties: id: type: integer created_at: type: string format: date-time updated_at: type: string format: date-time status: type: string nullable: true base_unit_of_measure_id: type: integer base_unit_of_measure: type: object description: Present when the relation is loaded. nullable: true properties: id: type: integer name: type: string unit_class_id: type: integer base_unit: type: boolean converted_unit_of_measure_id: type: integer converted_unit_of_measure: type: object description: Present when the relation is loaded. nullable: true properties: id: type: integer name: type: string unit_class_id: type: integer base_unit: type: boolean conversion_factor: type: number description: >- Multiply a quantity in `base_unit_of_measure` by this factor to get the quantity in `converted_unit_of_measure`. type: type: string enum: - SYSTEM - SKU product_id: type: integer nullable: true description: >- Required when `type=SKU`; null when `type=SYSTEM`. product: type: object nullable: true description: >- Present when the relation is loaded. Shape mirrors the standard product resource. additionalProperties: true product_alternate_skus: type: array description: Present when the relation is loaded. items: type: object additionalProperties: true base_unit_of_measure: description: Present when the relation is loaded. nullable: true allOf: - type: object description: >- A single unit of measure (e.g. "Pound", "Kilogram") belonging to a unit class. properties: id: type: integer created_at: type: string format: date-time updated_at: type: string format: date-time status: type: string nullable: true unit_class_id: type: integer unit_class: type: object description: Present when the relation is loaded. nullable: true properties: id: type: integer name: type: string base_class: type: boolean name: type: string description: type: string nullable: true base_unit: type: boolean description: >- True if this UOM is the base unit for its class. unit_conversion_rules: type: array description: Present when the relation is loaded. items: type: object description: > A rule converting from one unit of measure to another. `type=SYSTEM` rules apply globally for a class (e.g. 1 lb = 0.453592 kg). `type=SKU` rules override system rules for a specific product (`product_id`). properties: id: type: integer created_at: type: string format: date-time updated_at: type: string format: date-time status: type: string nullable: true base_unit_of_measure_id: type: integer base_unit_of_measure: type: object description: Present when the relation is loaded. nullable: true properties: id: type: integer name: type: string unit_class_id: type: integer base_unit: type: boolean converted_unit_of_measure_id: type: integer converted_unit_of_measure: type: object description: Present when the relation is loaded. nullable: true properties: id: type: integer name: type: string unit_class_id: type: integer base_unit: type: boolean conversion_factor: type: number description: >- Multiply a quantity in `base_unit_of_measure` by this factor to get the quantity in `converted_unit_of_measure`. type: type: string enum: - SYSTEM - SKU product_id: type: integer nullable: true description: >- Required when `type=SKU`; null when `type=SYSTEM`. product: type: object nullable: true description: >- Present when the relation is loaded. Shape mirrors the standard product resource. additionalProperties: true product_alternate_skus: type: array description: Present when the relation is loaded. items: type: object additionalProperties: true '401': description: Unauthorized content: application/json: schema: type: object properties: message: type: string '404': description: Unit class or UOM not found content: application/json: schema: type: object properties: message: type: string '422': description: UOM does not belong to the specified class content: application/json: schema: type: object properties: message: type: string security: - BearerAuth: [] components: securitySchemes: BearerAuth: type: http scheme: bearer description: >- Authenticate using a bearer token. To create a token, navigate to /settings/api-tokens and click Create API Token. ````