> For the complete documentation index, see [llms.txt](https://docs.snomed.org/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://docs.snomed.org/snomed-ct-user-guides/simplex-user-guide/how-to..../manage-subsets-in-simplex/update-a-subset-in-an-extension.md). # Update a Subset in an Extension **Note:** Simplex does not support the creation of SNOMED CT subsets. Subsets should be created in a dedicated tool, such as the Reference Set and Translation Tool. **Step 1: Prepare Your Input File** Simplex accepts input files in two formats: Excel files or export files from the Reference Set and Translation Tool. By following these steps, you can seamlessly integrate subsets into your SNOMED CT extension using Simplex. Should you have any questions or encounter any issues, please refer to our documentation or reach out to our support team for assistance. \\

Steps	References
1	Click "New Artifact"
2	Select artifact type. Select "Subset" from the list
3	Enter a name
4	Click create
5	Prepare Your Input File Simplex accepts input files in two formats: Excel files or export files from the Reference Set and Translation Tool.

*** | | | | | -------------------------------------------------- | ---------------------------------------------------------------------------------------- | ----------- | | **Excel File** | | | | 5.1.1 | Download the spreadsheet containing the current content in the Reference Set. |

| | 5.1.2 | Edit the content of the Reference Set in the spreadsheet according to your requirements. |

| | 5.1.3 | Upload the new version of the spreadsheet to Simplex. |

| | **Reference Set and Translation Tool Export File** | | | | 5.2.1 | Edit the Reference Set in the Reference Set & Translation Tool as needed. |

| | 5.2.2 | Export the Reference Set from the Reference Set & Translation Tool as a zip file. |

| | 5.2.3 | Upload the newly exported package as a zip file to Simplex. |

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