A MIB is an informational file that describes the settings that can be made with an F-Secure product and their settings for this product.
MIB is part of SNMP (Simple Network Managment Protocol). A MIB describes a set of objects, such as the F-Secure modules (e.g. Anti-Virus) that can be managed, and the properties and settings of these objects, such as a list of file extensions that are scanned or the name of the security profile which is in use. It is possible to restrict changing these properties - for an F-Secure Client Security host, the setting is "Final" in F-Secure Policy Manager - and add additional values to properties via Policy Manager, e.g. a new file extension that is to be scanned.