---
id: DATA-5
family: RT-DATA
level: core
profiles: [runtime]
posture: normative-target
added: "1.0"
changed: "1.0"
source: https://flowdrop.io/spec/rules/rt-data/data-5
specification: FlowDrop Workflow Specification 1.0-draft
licence: CC BY 4.0
---

# DATA-5 — Loopback and tool edges create no execution dependency

*RT-DATA (Part II) · level: core · profiles: runtime · added in 1.0*

## The rule

> **Normative.** This is the rule.
>
> 1. An edge into the reserved `loop_back` input port, and an edge that wires a tool to a consumer, create no execution dependency.
>
> 2. Neither is considered when the graph is checked for circular dependencies, and neither is considered when a node's readiness is evaluated.
>
> 3. A node whose only incoming edges are of those two kinds is therefore ready at once.
>
> 4. For tool edges this is required rather than convenient: a tool node never becomes a unit of execution, so it can never complete, and a tool edge that gated its consumer would starve it forever.

## Related rules

- Names: DATA-4, DATA-10
- Referenced by: DATA-4, DATA-10

---

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.