> ## Documentation Index > Fetch the complete documentation index at: https://docs.arcuserp.com/llms.txt > Use this file to discover all available pages before exploring further. # List open receivable invoices > Returns an account's open receivables (invoices and invoiced sales orders with a balance due), sorted by due date then issue date, excluding quotes, drafts, parent orders whose receivable sits on child invoices, and anything voided, cancelled, expired, or refunded. The response's totals report the true open count and amount for the whole account regardless of the page requested, and a `search` parameter can locate a specific document; requires `payments:read` scope. ## OpenAPI ````yaml /openapi.yaml get /payments/multi-invoice-candidates openapi: 3.1.0 info: title: Arcus ERP Public API version: 1.0.0 description: > Arcus ERP public REST API. Designed for external integrations and data migration. **Authentication.** Bearer token (API key) via the `Authorization` header. Format: `Authorization: Bearer ark_live_ent__` (or `ark_test_*` for sandbox). API keys are issued per-entity in **Settings > Developers > API Keys**. **Entity scoping.** The entity is encoded in the API key prefix; routes are flat (e.g. `/v1/accounts`, `/v1/orders`, `/v1/products`). A small set of platform endpoints (migration, reconciliation, events, webhook endpoints, API keys) use the `/v1/entities/{entity_id}/...` form -- those are noted in their tags. **Key capabilities.** - Related-resource hydration via `?expand[]=` (see `x-arcus-expand` on each resource). - Cursor-based pagination (`starting_after` / `ending_before` / `limit`). - Idempotency via the `Idempotency-Key` header. - Webhook events for asynchronous notification. - Conditional requests / ETag for cache validation. **Changelog.** Entries are dated and name every published contract whose MEANING moved, not only the ones whose field names changed. The narrative version of the same entries, written for integrators, is published at https://arcuserp.mintlify.app/changelog. **2026-09-22 (planned 2026-09-21), REORDER-BUYER-TRUTH: demand changed what it MEANS on three published contracts, with no field renamed.** An integrator that pins field names sees no breakage and different numbers, which is why this entry exists. - **Demand now counts build consumption.** `demand_avg_per_day` on the public product, kit and inventory-balance objects, and `daily_demand` / `demand_basis` / `net_suggested_qty` on `GET /v1/purchasing/reorder-report`, are composed from fulfilled sales lines PLUS posted `build_consume` inventory draws: each physical decrement of a product counts exactly once. The previous rule adopted an internal-consumption basis only when the sales blend was exactly zero, so a product both sold AND consumed into work orders planned as if the build draws did not exist. Products drawn into work orders move; on one production-shaped dataset five did, the largest from 0.05/day to 14.95/day. - **`demand_basis` now carries four values, not two:** `sales`, `sales_and_builds`, `builds` and `consumption`. A consumer with a two-branch reader (anything that is not `consumption` is `sales`) silently hides the two new ones. - **`current_demand_units` on `GET /v1/inventory/balances/:id` moved, by a second rule.** It counts committed-but-unshipped CUSTOMER demand, and it now counts a kit component's own line rather than its parent kit line, and excludes non-sales documents. On one production dataset 269 of 1,043 balance rows changed, 227 of them downward; the largest single move was 1,941 to 25, on a product whose open PURCHASE order line had been reported as customer demand. Re-baseline anything that alerts or reorders off this field. - `run_rate_30/90/180/365` and `blended_daily` on the same balance object move for the first reason above. - **Added, not changed:** `GET /v1/purchasing/reorder-report` accepts `demand_window` and returns the unit, cover-through and reorder-point-provenance fields documented on that operation; `order_multiple` is accepted and returned on the product-vendor doors. - **Volume note.** The `inventory.low_stock`, `inventory.out_of_stock` and `inventory.back_in_stock` webhook events are population-gated on `on_hand <= reorder_point`, and reorder points move with the demand above, so subscribers should expect a one-time step change in event volume around the release. servers: - url: https://api.arcuserp.com/v1 description: Arcus ERP API (accepts both live `ark_live_*` and test `ark_test_*` keys) - url: https://dev-api.arcuserp.com/v1 description: >- Dev sandbox API (test-only data, accepts `ark_test_*` keys against dev RDS) security: [] paths: /payments/multi-invoice-candidates: get: tags: - Payments summary: List open receivable invoices description: >- Returns an account's open receivables (invoices and invoiced sales orders with a balance due), sorted by due date then issue date, excluding quotes, drafts, parent orders whose receivable sits on child invoices, and anything voided, cancelled, expired, or refunded. The response's totals report the true open count and amount for the whole account regardless of the page requested, and a `search` parameter can locate a specific document; requires `payments:read` scope. operationId: listMultiInvoiceCandidates parameters: - name: account_id in: query required: true schema: type: string format: uuid description: Account to list open invoices for. - name: limit in: query schema: type: integer default: 100 maximum: 200 - name: offset in: query schema: type: integer default: 0 - name: search in: query required: false schema: type: string maxLength: 64 description: > Optional. Filters the list to open documents whose order number OR invoice number contains this string (case-insensitive), or whose balance_due starts with it. total_open_count/amount stay full-account; filtered_count/amount match this filter. responses: '200': description: List of open invoices content: application/json: schema: type: object properties: data: type: array items: type: object properties: id: type: string format: uuid order_number: type: string invoice_number: type: string nullable: true description: The document's own invoice number NULL until it is invoiced. Label = COALESCE(invoice_number: null order_number).: null invoice_status: type: string nullable: true description: >- The document's own invoice status. Read together with invoice_number and source_order_number to compose the display identity (ar-helpers.mjs::resolveInvoiceDisplayIdentity). source_order_number: type: string nullable: true description: The parent sales order's number for a child invoice NULL when the row has no parent. Rendered as the secondary reference beside the label.: null order_total: type: number amount_paid: type: number balance_due: type: number document_type: type: string business_date: type: string format: date description: >- Calendar day the document was issued: COALESCE(invoice_date, order_date, created_at) projected to the entity calendar day (date-boundaries.mjs::businessCalendarDateExpr). A YYYY-MM-DD string, never an instant. Declared date-time until 2026-09-16, when the implementation was brought into line with due_date and with every other AR reader. is_invoice_doc: type: boolean description: >- Two-mode invoice-document verdict (ar-helpers.mjs::arInvoiceLedgerClause). due_date: type: string format: date nullable: true description: >- Calendar day the receivable is due, as YYYY-MM-DD (date-boundaries.mjs::businessCalendarDateExpr). Stored as a timestamptz whose value is a midnight-UTC carrier on 44,052 of 44,056 live values, so it is projected to a calendar day rather than served as an instant a client would render in its own zone, a day early. payment_status: type: string meta: type: object properties: count: type: integer description: Rows in THIS page (loaded page length). limit: type: integer offset: type: integer total_open_count: type: integer description: >- TRUE count of all open documents for the account (unbounded by limit). total_open_amount: type: number description: >- TRUE sum of balance_due across all open documents (unbounded by limit). search: type: string nullable: true description: Echo of the active search filter (null when none). filtered_count: type: integer description: >- Open documents matching the search filter (== total_open_count when no search). filtered_amount: type: number description: >- Sum of balance_due matching the search filter (== total_open_amount when no search). '400': $ref: '#/components/responses/Error' '401': $ref: '#/components/responses/Error' '403': $ref: '#/components/responses/Error' security: - ApiKeyAuth: [] components: responses: Error: description: Error response (400/401/403/404/409/422/429/500) content: application/json: schema: $ref: '#/components/schemas/ErrorEnvelope' schemas: ErrorEnvelope: type: object description: | Canonical error response envelope. All API errors use this shape. required: - error - code properties: error: type: string description: Machine-readable error key example: not_found code: type: string description: Machine-readable error code (often same as error) example: not_found type: type: string enum: - validation_error - permission_error - not_found - conflict - rate_limit - internal - expand_error - not_implemented example: not_found hint: type: string description: Human-readable one-sentence explanation (English) example: >- The requested order does not exist or does not belong to this entity. param: type: string description: The parameter that caused the error, if applicable example: expand[0] required: type: string description: The scope required (only on insufficient_scope errors) example: accounts:read request_id: type: string description: >- Unique request ID for support tracing (maps to CloudWatch log stream) example: req_abc123 securitySchemes: ApiKeyAuth: type: http scheme: bearer description: | API key issued per entity via Settings > Developers > API Keys. Each key carries scopes (e.g. orders:read, products:write). Bearer token format: Authorization: Bearer ark_live_ent__ Test keys use ark_test_ent__. Both are issued per entity via Settings > Developers > API Keys. ```` This documentation is built and hosted on [Mintlify](https://mintlify.com), a developer documentation platform.