generated: '2026-07-17'
method: derived
source: openapi/apperio-openapi-original.yml — derived from the /api/v1 path hierarchy and glossary (schemas are inline, no components.schemas)
description: >-
  Entity-relationship graph for the Apperio API, derived from the resource path
  structure. Apperio is a two-sided legal-spend platform; the core entities are
  matters (a.k.a. engagements), invoices, matter tags, users/tokens, and
  business invoice attributes.
entities:
  - name: Matter
    aka: [Engagement]
    path: /api/v1/matters/{matter-id}
    id_param: matter-id
    description: A unit of legal work (matter/engagement) that spend is tracked against.
    relationships:
      - has_many: Invoice
        via: matter-id
      - has_many: MatterTagLink
        via: matter-id
  - name: Invoice
    path: /api/v1/ebilling/invoices/{invoice-id}
    id_param: invoice-id
    description: A law-firm invoice moving through an e-billing approval workflow.
    relationships:
      - belongs_to: Matter
        via: matter-id
      - has_one: ApprovalWorkflow
        via: invoice-id
      - has_many: BusinessAttribute
        via: name
  - name: ApprovalWorkflow
    path: /api/v1/ebilling/invoices/{invoice-id}/approval-workflow
    description: The approval state machine for an invoice (approve / reject / adjust / query).
    relationships:
      - belongs_to: Invoice
        via: invoice-id
      - has_many: ApprovalState
        via: invoice-approval-state-id
  - name: BusinessAttribute
    path: /api/v1/ebilling/invoices/business-attributes/{name}
    id_param: name
    description: Custom business attributes attachable to invoices.
  - name: MatterTagSet
    path: /api/v1/filter/matter-tag-sets/{matter-tag-set-id}
    id_param: matter-tag-set-id
    description: A named grouping of matter tags used for filtering/segmentation.
    relationships:
      - has_many: MatterTag
        via: matter-tag-set-id
  - name: MatterTag
    path: /api/v1/filter/matter-tag-sets/{matter-tag-set-id}/matter-tags/{matter-tag-id}
    id_param: matter-tag-id
    description: A tag within a tag set; can be linked to matters.
    relationships:
      - belongs_to: MatterTagSet
        via: matter-tag-set-id
      - has_many: MatterTagLink
        via: matter-tag-id
  - name: MatterTagLink
    path: /api/v1/filter/matter-tag-sets/{matter-tag-set-id}/matter-tags/{matter-tag-id}/links/{link-id}
    id_param: link-id
    description: The association between a matter tag and a matter.
    relationships:
      - belongs_to: MatterTag
        via: matter-tag-id
      - belongs_to: Matter
        via: matter-id
  - name: ApiToken
    path: /api/v1/users/tokens/{token-id}
    id_param: token-id
    description: A user-scoped API token used to authenticate requests.
  - name: Analytics
    path: /api/v1/data/analytics
    description: Aggregated legal-spend analytics powering Apperio's reporting visualisations.