Subject to any technical implementing measures adopted under paragraph 5, the competent national authorities may adopt guidelines and, where necessary, issue instructions concerning the circumstances in which providers are required to notify personal data breaches, the format of such notification and the manner in which the notification is to be made. They shall also be able to audit whether providers have complied with their notification obligations under this paragraph, and shall impose appropriate sanctions in the event of a failure to do so.
Providers shall maintain an inventory of personal data breaches comprising the facts surrounding the breach, its effects and the remedial action taken which shall be sufficient to enable the competent national authorities to verify compliance with the provisions of paragraph 3. The inventory shall only include the information necessary for this purpose.