Data licences show allow redistribution

The discussion around the addition of test data should state that all new files should have a licence which allows for public redistribution and that files with a restrictive licence will be rejected by the IAO. This is currently implicit but it should be stated explicitly to avoid ambiguity.

Locate the documentation or discussion covering the addition of test data, since no specific file is named in the issue. Read the existing wording about licences and update it to state that new files must allow public redistribution and that restrictive licences will be rejected by the IAO. Done means the requirement is explicit and unambiguous.

Written by the indexing model from the issue text.