Volume 4 of the CBB Rulebook for the most part applies only to investment firm licensees, and to individuals undertaking key functions in those licensees (so-called 'approved persons'). (Representative offices are subject to the relevant requirements in Volume 5 of the CBB Rulebook.) Volume 4 also provides for the registration of persons carrying on the business of an administrator, with respect to financial instruments. Most of the content of Volume 4 therefore only has the formal status of a Directive.