Strategic Modeling custom dimension upload format

Summary:

Can someone provide the format of the file to use to upload a custom dimension in strategic modeling? There is nothing in the documentation on the format, and there is no option to export when you create a few members.

Content (please ensure you mask any confidential information):

Version (include the version you are using, if applicable):

25.07

Code Snippet (add any code snippets that support your topic, if applicable):