In KV2 there are SUB records available with ISSN and no DOI. For some reason some ISSN have been disseminated although the serial is not active (and will never be).
For those cases, I would need an exclusion list like the one for the ISBN in KV2. I could then add the ISSN to no be reused to the list with a comment.
I have already the Eco Surv Baltic States and Ukraine ISSN to add