You’re planning to visit a historical archive, and while you have looked on line in an effort to discover their rules about the further dissemination of their materials, you have not been able to find them. Compose an email to the archivist requesting permission to include the materials you will obtain from the archive in a data project you plan to share.
Here are some things your request might have included:
your institutional affiliation;
the nature of your research project;
why the data are important for your project;
why you would like to share the data;
in what specific data repository you plan to share the data and what that implies for their accessibility;
when you would like to share the data;
when you will be visiting the archive;
an offer to discuss the matter with the archivist when you are on site.
QDR has a template for such an email that you might send after conducting your research if you did not find this information out during your time at the archive. If you can, though, it is better to ask these sorts of questions before or during your research at the archive.