Preprint
Authors are obliged to declare in the cover letter if the version of their submission has been deposited on a preprint server, and provide any associated accession numbers or DOIs. Usually, authors are permitted to post their non-peer-reviewed original research manuscripts to community preprint servers, i.e., revised manuscripts after being peer-reviewed should not be posted.
If the article has already been published, authors need to clearly indicate on the preprint where the article has been published and link to the article’s page in the journal.