# Declare a workflow's inputs and outputs

Control / subflow

A variant of [Call a reusable workflow](https://meridian.online/operations/call-a-reusable-workflow).

Mark the points where a reusable workflow receives rows, files or variables from its caller and hands results back.

Page: <https://meridian.online/operations/call-a-reusable-workflow/declare-workflow-inputs-and-outputs>

## Status

Not built yet.

arcform does not do this yet; it would live in how a Protocol runs. [Its place on the roadmap](https://meridian.online/roadmap#call-a-reusable-workflow)

## What other tools call it

Meridian's classification; an independent blind rating agreed on 95.7% of 324 rows (variant, version 3).

- Alteryx Designer: [`Macro Input`](https://help.alteryx.com/current/en/designer/tools/interface-tools/macro-input-tool.html) (read 2026-09-27)
- Alteryx Designer: [`Macro Input In-DB`](https://help.alteryx.com/current/en/designer/tools/in-database/macro-input-in-db-tool.html) (read 2026-09-27)
- Alteryx Designer: [`Macro Output`](https://help.alteryx.com/current/en/designer/tools/interface-tools/macro-output-tool.html) (read 2026-09-27)
- Alteryx Designer: [`Macro Output In-DB`](https://help.alteryx.com/current/en/designer/tools/in-database/macro-output-in-db-tool.html) (read 2026-09-27)
- EasyMorph: [`Input`](https://help.easymorph.com/doku.php?id=transformations:input) (read 2026-09-27)
- Apache Hop: [`Injector`](https://hop.apache.org/manual/latest/pipeline/transforms/injector.html) (read 2026-09-27)
- Apache Hop: [`Mapping input`](https://hop.apache.org/manual/latest/pipeline/transforms/mapping-input.html) (read 2026-09-27)
- Apache Hop: [`Mapping output`](https://hop.apache.org/manual/latest/pipeline/transforms/mapping-output.html) (read 2026-09-27)
- KNIME Analytics Platform: [`Container Input (Credentials)`](https://api.hub.knime.com/nodes/*T0ZphJki5btJ9yNo?details=full) (read 2026-09-27)
- KNIME Analytics Platform: [`Container Input (File)`](https://api.hub.knime.com/nodes/*LY4Cs9xl2pySTAd8?details=full) (read 2026-09-27)
- KNIME Analytics Platform: [`Container Input (JSON)`](https://api.hub.knime.com/nodes/*nBH3LP3nmxGrE_0X?details=full) (read 2026-09-27)
- KNIME Analytics Platform: [`Container Input (Row)`](https://api.hub.knime.com/nodes/*jTxkQKXn9DkKRLfj?details=full) (read 2026-09-27)
- KNIME Analytics Platform: [`Container Input (Table)`](https://api.hub.knime.com/nodes/*oyBCABe-opg-Assd?details=full) (read 2026-09-27)
- KNIME Analytics Platform: [`Container Input (Variable)`](https://api.hub.knime.com/nodes/*VLtSgPwCn2dZrJuf?details=full) (read 2026-09-27)
- KNIME Analytics Platform: [`Container Output (File)`](https://api.hub.knime.com/nodes/*3otqVNwkxsXZrb33?details=full) (read 2026-09-27)
- KNIME Analytics Platform: [`Container Output (JSON)`](https://api.hub.knime.com/nodes/*zOsWiRPweohTpd8S?details=full) (read 2026-09-27)
- KNIME Analytics Platform: [`Container Output (Row)`](https://api.hub.knime.com/nodes/*BQZdYIJZv06Q9UiY?details=full) (read 2026-09-27)
- KNIME Analytics Platform: [`Container Output (Table)`](https://api.hub.knime.com/nodes/*sma6KF7pwZETNOdi?details=full) (read 2026-09-27)
- KNIME Analytics Platform: [`Workflow Input`](https://api.hub.knime.com/nodes/*SjCp1LKYnOOV8KMB?details=full) (read 2026-09-27)
- KNIME Analytics Platform: [`Workflow Output`](https://api.hub.knime.com/nodes/*9xSDVHDks-V8M3VU?details=full) (read 2026-09-27)
- Apache NiFi: [`Input Port`](https://nifi.apache.org/nifi-docs/user-guide.html) (read 2026-09-27)
- Apache NiFi: [`Output Port`](https://nifi.apache.org/nifi-docs/user-guide.html) (read 2026-09-27)
- Pentaho Data Integration: [`Injector`](https://docs.pentaho.com/pdia-data-integration/9.3-data-integration/pdi-transformation-steps-reference-overview) (read 2026-09-27)
- Pentaho Data Integration: [`MapReduce Input`](https://docs.pentaho.com/pdia-data-integration/9.3-data-integration/pdi-transformation-steps-reference-overview) (read 2026-09-27)
- Pentaho Data Integration: [`MapReduce Output`](https://docs.pentaho.com/pdia-data-integration/9.3-data-integration/pdi-transformation-steps-reference-overview) (read 2026-09-27)
- Pentaho Data Integration: [`Mapping Input Specification`](https://docs.pentaho.com/pdia-data-integration/9.3-data-integration/pdi-transformation-steps-reference-overview) (read 2026-09-27)
- Pentaho Data Integration: [`Mapping Output Specification`](https://docs.pentaho.com/pdia-data-integration/9.3-data-integration/pdi-transformation-steps-reference-overview) (read 2026-09-27)