The FDA released an updated version of its Risk Evaluation and Mitigation Strategies: Modifications and Revisions Guidance for Industry as Revision 2.  Originally issued in 2015 (here) and updated again in 2019, the June 2020 version contains much the same information but provides updates as to timetables, additional categories of PAS, CBE, and CBE 30 supplemental changes.

If you are at all involved in the issuance of “revisions” or “modifications” (minor or major) as described in the guidance, you should read this document closely so as to not run afoul of the restated requirements, albeit there are still some judgement calls as to which filing category some of the changes fall into.  That is likely why the FDA has said that if you submit a CBE for a change and they disagree on the classification, you will get a notice that they are changing your submission to a PAS.  Happy filing!