> ## Documentation Index > Fetch the complete documentation index at: https://terminal49.com/docs/llms.txt > Use this file to discover all available pages before exploring further. # Create an account custom field definition > Create a custom field definition on your Terminal49 account to attach structured metadata, like reference codes or enums, to shipments and containers. Creates a custom field definition on your account. The API always creates the definition on the authenticated user's account, whatever `account_id` you pass. ## Request body Send `template_id`, or all of `entity_type`, `api_slug`, `display_name` and `data_type`. | Parameter | Required | Description | | - | - | - | | `entity_type` | Without `template_id` | The entity type this field applies to: `Shipment` or `Cargo` (containers). Other values return `422`. | | `api_slug` | Without `template_id` | Unique identifier for the field | | `display_name` | Without `template_id` | Human-readable name for the field | | `data_type` | Without `template_id` | Data type for values (for example: `short_text`, `number`, `date`, `reference`) | | `template_id` | No | ID of a Terminal49 template definition to copy. The template supplies `entity_type`, `api_slug`, `display_name`, `data_type` and the other attributes. Attributes you send override the template's values. An unknown `template_id` returns `404`. | | `description` | No | Optional description of the field's purpose | | `validation` | No | Validation rules (for example: `required`, `pattern`, `max_length`) | | `default_format` | No | Default format string for numbers or dates | | `default_value` | No | Default value for new custom fields | | `reference_type` | No | Required when `data_type` is `reference` | | `reference_number` | No | Whether values are reference numbers. Terminal49 indexes reference-number values for global search and document matching. Defaults to `false`. | | `sensitive` | No | Whether the field is sensitive. Sensitive fields are hidden from recipients of externally shared container views. Defaults to `false`. | | `inline_option_creation` | No | Whether users can add a new option while entering an `enum` or `enum_multi` value in the Terminal49 app. Defaults to `false`. | ## OpenAPI ````yaml post /accounts/{account_id}/custom_field_definitions 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: Account paths: /accounts/{account_id}/custom_field_definitions: parameters: - schema: type: string format: uuid name: account_id in: path required: true description: >- Your account ID. The API always uses the account of the authenticated user. post: tags: - Custom Field Definitions summary: Create a custom field definition description: >- Creates a custom field definition for your account. Pass `template_id` to copy a Terminal49 template; attributes you send override the template's values. operationId: post-account-custom-field-definitions 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: entity_type: type: string enum: - Shipment - Cargo description: '`Cargo` means containers.' 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' template_id: type: string format: uuid description: ID of a Terminal49 template definition to copy. reference_number: type: boolean description: >- Whether values are reference numbers. Terminal49 indexes reference-number values on account definitions for global search and document matching. default: false sensitive: type: boolean description: >- Whether the field is sensitive. Sensitive fields are hidden from recipients of externally shared container views. default: false inline_option_creation: type: boolean description: >- Whether users can add a new option while entering an `enum` or `enum_multi` value in the Terminal49 app. default: false description: >- Send `template_id`, or all of `entity_type`, `api_slug`, `display_name` and `data_type`. With `template_id`, the template supplies any of those four you leave out. responses: '201': description: Created content: application/json: schema: type: object properties: data: $ref: '#/components/schemas/custom_field_definition' links: $ref: '#/components/schemas/link-self' '404': description: '`template_id` does not match a Terminal49 template.' content: application/json: schema: type: object properties: errors: type: array items: $ref: '#/components/schemas/error' example: errors: - status: '404' title: Not Found '422': $ref: '#/components/responses/UnprocessableEntity' components: schemas: custom_field_value: description: Raw custom field value (type depends on definition) oneOf: - type: string nullable: true - type: number - type: boolean - type: array items: type: string - type: object additionalProperties: true 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 - Cargo description: >- The entity type this definition applies to. `Cargo` means containers. 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' reference_number: type: boolean description: >- Whether values are reference numbers. Terminal49 indexes reference-number values on account definitions for global search and document matching. sensitive: type: boolean description: >- Whether the field is sensitive. Sensitive fields are hidden from recipients of externally shared container views. inline_option_creation: type: boolean description: >- Whether users can add a new option while entering an `enum` or `enum_multi` value in the Terminal49 app. template_id: type: string format: uuid nullable: true description: ID of the Terminal49 template this definition was copied from. has_data: type: boolean description: Whether any entity has a value for this definition. created_at: type: string format: date-time updated_at: type: string format: date-time discarded_at: type: string format: date-time nullable: true description: When the definition was archived. required: - entity_type - api_slug - display_name - data_type relationships: type: object properties: account: type: object description: The owning account. `null` for Terminal49 templates. properties: data: type: object nullable: true required: - type - id properties: id: type: string format: uuid type: type: string enum: - account created_by: type: object description: The user who created the definition. properties: data: type: object properties: type: type: string enum: - user id: type: string format: uuid required: - type - id nullable: true options: type: object properties: data: type: array items: type: object required: - type - id properties: id: type: string format: uuid type: type: string enum: - custom_field_option required: - id - type link-self: title: link type: object properties: self: type: string description: >- Absolute URL of the request, including its query string as sent. On a create, this is the collection URL the request was posted to, not the URL of the new resource. error: title: Error model type: object properties: detail: type: string nullable: true title: type: string nullable: true source: type: object nullable: true properties: pointer: type: string nullable: true parameter: type: string nullable: true code: type: string nullable: true status: type: string nullable: true meta: type: object nullable: true additionalProperties: true responses: UnprocessableEntity: description: Unprocessable Entity content: application/json: schema: type: object properties: errors: type: array items: $ref: '#/components/schemas/error' example: errors: - status: '422' source: pointer: /data/attributes/label title: Unprocessable Entity detail: Label can't be blank code: blank 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.