---
id: R2
family: GR-VAL
level: core
profiles: [storage-api]
posture: normative-target
added: "1.0"
changed: "1.0"
source: https://flowdrop.io/spec/rules/gr-val/r2
specification: FlowDrop Workflow Specification 1.0-draft
licence: CC BY 4.0
---

# R2 — Node ids are unique within a workflow

*GR-VAL (Part I) · level: core · profiles: storage-api · added in 1.0*

A workflow is read by keying its nodes on their ids. Two nodes sharing one id would silently collapse to whichever was read last, so the duplicate is refused at save instead.

## The rule

> **Normative.** This is the rule.
>
> 1. Node `id`s must be unique within a workflow.
>
> 2. A workflow containing two nodes with the same `id` is refused with the error code `R2_NODE_DUPLICATE_ID`, and the save does not take effect.

## Why

Recorded under OPEN-4.

---

Rule identifiers are permanent and are never renumbered. This specification carries
no implementation status: each implementation publishes its own standing against
these rules. Licensed CC BY 4.0.