> ## Documentation Index > Fetch the complete documentation index at: https://terminal49-feat-trade-intel-sdk.mintlify.site/llms.txt > Use this file to discover all available pages before exploring further. # Update a custom field definition > Update a custom field definition in the Terminal49 API, including its display label, data type constraints, and enum option set for shipments or containers. Update an existing custom field definition. ## Path parameters | Parameter | Description | | - | - | | `id` | The unique identifier of the custom field definition | ## Request body Provide the fields you want to update, such as `display_name`, `description`, `validation`, or `default_format`. ## Notes You cannot change `api_slug`, `entity_type`, or `data_type` after creation. ## OpenAPI ````yaml patch /custom_field_definitions/{id} openapi: 3.0.0 info: title: Terminal49 API Reference version: 0.2.0 contact: name: Terminal49 API support url: https://www.terminal49.com email: support@terminal49.com description: >- The Terminal 49 API offers a convenient way to programmatically track your shipments from origin to destination. Please enter your API key into the "Variables" tab before using these endpoints within Postman. x-label: Beta termsOfService: https://www.terminal49.com/terms servers: - url: https://api.terminal49.com/v2 description: Production security: - authorization: [] tags: - name: Containers - name: Custom Field Definitions - name: Custom Field Options - name: Custom Fields - name: Shipments - name: Locations - name: Events - name: Tracking Requests - name: Webhooks - name: Webhook Notifications - name: Ports - name: Metro Areas - name: Terminals - name: Routing (Paid) - name: Documents - name: Email Submissions - name: Document Schemas - name: Search - name: Parties - name: Trade Intelligence description: >- Trade intelligence answers questions about who imports what into the US, from where, on which carriers, and how that changes over time. The data is US import bill-of-lading records (US Customs vessel manifests): every ocean container landed at a US port (plus US-bound cargo landed at Vancouver, BC) from January 2022 to today, refreshed daily. It does not include air freight, exports, or domestic moves. **Access.** Trade intelligence is enabled per account. Accounts without it receive `403 Forbidden` with `{"error": "Trade intelligence is not enabled for this account"}`; contact sales@terminal49.com to enable it. Requests are limited to roughly 120 per minute per account (`429` with `{"error": "Rate limit exceeded; retry in a minute"}`). **Format.** These endpoints accept and return plain JSON, not JSON:API. Send `Content-Type: application/json` on `POST` requests and authenticate exactly like every other v2 endpoint (`Authorization: Token YOUR_API_KEY`). **Typical flow.** Resolve a name or product first, then analyze: `companies/search` or `commodities/search` give you the exact `company_name` or `hs4` to pass to `companies/profile`, `importers/top`, `trends`, or `breakdown`. Container and bill of lading numbers go straight to `containers/lookup` and `bills_of_lading/lookup`. **Reading the numbers.** - **Volume is physical containers.** Each box is counted once, even when it appears on several bills of lading. A container carrying several HS codes counts once per code and companies can share containers, so do not add volumes across HS codes or companies; take market totals from `trends` or `breakdown` without a company filter. - **Estimated value is a modelled USD estimate**, not the declared customs value. - **The current month is partial.** `trends` and `breakdown` include it by default; `companies/profile` and `importers/top` use full calendar months. Compare full months against the same months a year earlier. - **Absent volume is not small volume.** Importers can ask US Customs to withhold their name from manifests, and much large-retail freight is booked under forwarders or suppliers. Treat a company's figures as a floor, never as its size. - **One company, many names.** Company names are normalized but split by state, and large importers use several names (distribution, merchandising, and DC entities). Related entities are separate companies; report them separately. `companies/search` ranks by match quality, not by size. - **Companies are the consignee or notify party on the bill.** Forwarders, NVOCCs, and customs brokers appear alongside cargo owners. A high notify-party share, or LOGISTICS, FREIGHT, SHIPPING, CUSTOMS, or BROKERAGE in the name, usually indicates a logistics provider. - **Carriers, countries, and ports use the manifests' spellings**, and carriers appear under spelling variants (for example `CMA CGM` and `CMA CGM AMERICA LLC`). Filter with substrings and merge variants before computing shares. - **HS4 descriptions are truncated.** Check `common_goods` from `commodities/search` before relying on a code. paths: /custom_field_definitions/{id}: parameters: - schema: type: string name: id in: path required: true description: Custom field definition ID patch: tags: - Custom Field Definitions summary: Update a custom field definition operationId: patch-custom-field-definitions-id requestBody: content: application/json: schema: type: object properties: data: type: object required: - type - attributes properties: type: type: string enum: - custom_field_definition attributes: type: object properties: display_name: type: string description: type: string nullable: true validation: type: object nullable: true additionalProperties: true default_format: type: string nullable: true default_value: $ref: '#/components/schemas/custom_field_value' responses: '200': description: OK content: application/json: schema: type: object properties: data: $ref: '#/components/schemas/custom_field_definition' links: $ref: '#/components/schemas/link-self' components: schemas: custom_field_value: description: Raw custom field value (type depends on definition) nullable: true oneOf: - type: string - type: number - type: boolean - type: array items: type: string - type: object custom_field_definition: title: Custom field definition type: object properties: id: type: string format: uuid type: type: string enum: - custom_field_definition attributes: type: object properties: entity_type: type: string enum: - Shipment - Container - TrackingRequest api_slug: type: string display_name: type: string description: type: string nullable: true data_type: type: string enum: - short_text - number - date - datetime - boolean - enum - enum_multi - reference reference_type: type: string nullable: true validation: type: object nullable: true additionalProperties: true default_format: type: string nullable: true default_value: $ref: '#/components/schemas/custom_field_value' required: - entity_type - api_slug - display_name - data_type required: - id - type link-self: title: link type: object properties: self: type: string format: uri securitySchemes: authorization: name: Authorization type: apiKey in: header description: >- Use a Terminal49 API key in the `Authorization` header with the `Token` prefix. `Authorization: Token YOUR_API_KEY` ```` This documentation is built and hosted on [Mintlify](https://mintlify.com), a developer documentation platform.