---
id: SG-10
family: RT-SG
level: extended
profiles: [runtime]
posture: normative-target
added: "1.0"
changed: "1.0"
source: https://flowdrop.io/spec/rules/rt-sg/sg-10
specification: FlowDrop Workflow Specification 1.0-draft
licence: CC BY 4.0
---

# SG-10 — A loopback driven from the trigger port belongs to no branch

*RT-SG (Part II) · level: extended · profiles: runtime · added in 1.0*

## The rule

> **Normative.** This is the rule.
>
> Where a loopback edge's source is the reserved `trigger` port, the re-entry it drives is attributed to no branch.


## What it means

A loopback edge's branch is read off the port it leaves its source by, and
`trigger` is a control signal, not a named branch — leaving by it extracts to
no branch at all. Where a source declares branches and gates re-entry by
which one fired, a loopback edge driven from `trigger` sits outside that
gate: the re-entry it drives happens regardless of which branch, if any, the
source reports as active.

## Example

A loopback edge leaves its source by the reserved trigger port rather than by
a branch port such as the one whose handle ends in `False`.

```json title="The source handle of a loopback edge leaving the trigger port"
"gw.1-output-trigger"
```

```json title="The branch name extracted from it" verdict="unbranched"
""
```

An empty branch name is what attributes a loopback edge to no branch; the
same extraction on a handle ending in `False` yields `False`.

## Related rules

- Names: SG-7

---

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.