1. A method for authority checking in a computer based control system for industrial process or manufacturing control, the control system comprising software means for representing real world entities as software objects which hold functions and information related to said real world entities, means for organizing software objects in at least two hierarchical structures, means for identifying a user at the time of log-in to the system, and means for identifying a logged-in user with a user identity between the time of log-in and log-out, comprising the following steps: inserting a first software object into at least two hierarchical structures, adding a security settings to each of at least a second and a third software objects, which are placed at positions higher than the first software object, one in each of the said at least two hierarchical structures, inheriting to the first software object through said at least two hierarchical structures the security settings that are associated with said at least second and third software objects, determining, based on the user identity and on the inherited security settings, a user's authority to access at least one function or piece of information of the first software object.