---
id: EXPO-13
family: GR-EXPO
level: core
profiles: [storage-api, runtime]
posture: normative-target
added: "1.0"
changed: "1.0"
source: https://flowdrop.io/spec/rules/gr-expo/expo-13
specification: FlowDrop Workflow Specification 1.0-draft
licence: CC BY 4.0
---

# EXPO-13 — A node type can hide an output outright

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

## The rule

> **Normative.** This is the rule.
>
> 1. Where a node type marks an output port `exposed: false`, that output is stripped from every instance's result unconditionally, and no instance override can restore it.
>
> 2. Otherwise the instance's own override decides, then the node type's default exposure, and a port with none of these resolves as exposed.


## What it means

Two node-type-level signals both start an output hidden, but only one of
them can be reversed by the workflow's own instance override. Marking a port
`exposed: false` says the port does not exist at all: nothing an instance
records can restore it. The node type's default exposure, by contrast, is
only a starting position — the instance's own override decides over it, and
only the node type's default is consulted when the instance has recorded
none.

## Example

```json title="A result carrying an output the node type declares does not exist (exposed: false)" verdict="stripped"
{"result": "ok", "debug": "internal trace"}
```

```json title="A different port, merely hidden by the node type's default exposure" verdict="stripped"
{"throttled": true}
```

```json title="A default-hidden port the instance overrides back on" verdict="kept"
{"debug": "now wanted"}
```

The first case takes no override — none could change the outcome. The third
starts from the same kind of hiding as the second and reverses it, because a
default is only ever a starting position.

## Related rules

- Names: EXPO-2, EXPO-11
- Referenced by: EXPO-11, DATA-8

---

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.