Negaliu suprasti šio sakinio prasmės, gal kas padės:

With essential security functions replacement of an employee is guaranteed.

Visas kontekstas (kalbama apie IT saugumo politiką):

SECURITY ORGANISATION AND INFRASTRUCTURE
5.1.	Essential decisions regarding security are taken by chief security 
in cooperation with management.
5.2.	Security situation is reviewed once a month when performing company 
risk evaluation.
5.3.	Liabilities in the field of security have been determined by 
internal regulations, orders of the general director and job 
descriptions. With essential security functions replacement of an 
employee is guaranteed.
5.4.	Punishments determined by standing orders of the house are applied 
in case of misuse of property available to an employee.