# Update Entity Type Relation

Modify a relation's allowed subject entity types.

Endpoint: PATCH /resources/entity-types/v1/{key}/relations/{relationKey}
Version: 1.0
Security: bearer

## Request fields (application/json):

  - `key` (string, required)
    Example: "reader"

  - `subjectEntityKeys` (array, required)
    Example: ["copywriter","customer"]

## Response 200 fields (application/json):

  - `vendorId` (string, required)
    Example: "123e4567-e89b-12d3-a456-426614174000"

  - `targetEntityTypeKey` (string, required)
    Example: "book"

  - `key` (string, required)
    Example: "reader"

  - `subjectEntityTypeKeys` (array, required)
    Example: ["copywriter","customer"]