What it is (ADR-028, item 5)
Bulk changes to ad account spending limits (spend_cap): set, lower, reset the counter or remove the limit — on several accounts at once, over the official Marketing API, with your token.
Who, and on which accounts
Owner and Head only. Only ad accounts owned by your BM; accounts partners shared with you are not changed. If you have a personal daily budget limit, you can only lower an account's limit or set one where there was none; raising, resetting or removing it is for an Owner or Head without a personal limit.
Check after each write
After every change AdFleet reads the limit back from Meta and tells you if the value doesn't match.