Immediately open (gold open access) channels are journals which have all their content open to all readers. Typically, their operating costs are covered by article processing charges (APCs). APC is not a sufficient reason to put an open access channel in Category 0. Quite a trustworthy register of quality open access journals is the Directory of Open Access Journals, which is integrated into the Publication Forum database. However, it should be noted that not all journals listed in DOAJ meet the criteria for Level 1, for example regarding the composition of the editorial board and authorship.