---
id: R4.d
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/r4-d
specification: FlowDrop Workflow Specification 1.0-draft
licence: CC BY 4.0
---

# R4.d — An exposure entry must name a port the node declares

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

## The rule

> **Normative.** This is the rule.
>
> 1. A workflow exposure entry's `port` must be declared by the named node: as an input parameter for an entry on the input side, as an output for one on the output side.
>
> 2. An entry naming an undeclared port is refused at `schema.{side}.{index}`.
>
> 3. Where the node's executor cannot be resolved the port cannot be checked, so this check and R10 are skipped for that entry rather than guessed at; the skip is narrower than the entry, and R4.a's name format and R4.b's uniqueness (both decided from the entry alone) are still reported.

## Related rules

- Names: R4.a, R4.b, R10
- Referenced by: R4.c, R10

---

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.