SNMP MIB Terminology:

  MIB - A Management Information Base. It's a database, essentially, just not
        a familiar RDBMS. Every device that supports SNMP has one, which you can
        query and update, if you know it's schema. The schema of a MIB is 
        defined in a set of MIB files where each file contains modular portions
        of the schema. Since each device may implement a different overall 
        schema, a module-based approach allows for that sort of flexibility
        
        
  MIB File - An ASCII text file written according to the SMI format, which is 
             based on and defined using ASN.1. The MIB file is used to define 
             and describe the schema of an SNMP MIB, or a portion of one.
             
             
  MIB Object - A queriable entity from an SNMP MIB. In a MIB browser, this is 
               often described as a leaf or column. Each MIB Object is defined 
               in a MIB file using the OBJECT-TYPE syntax. A MIB Object would
               define the following properties:

    object_type:    The name of this object in the SMI OBJECT-TYPE definition 
                    in the MIB File.
    type_oid:       The OID of the object_type, as defined in the MIB.
    index_name[n]:  The name of the n-th index of this object-type, as defined in
                    the MIB. (only valid for tables, table entries, and columns)

                    
  Object Instance - To borrow terminology from Object Oriented Programming, if a
                    MIB Object is a class definition, an Object Instance is an 
                    instance of an object of a class. In addition to the 
                    properties of a MIB Object, it has the following which 
                    establish it's identity and value:

    value:         The actual value, as returned from a query to a device.
    instance_id:   The specific identity of this object instance in a device in
                   relation to it's object_type. It is a portion of an OID 
                   string that is composed by the concatenation of one or more 
                   indices.
    index_val[n]:  The value of the n-th index of this object's instance
    full_oid:      The full identifier for this particular object instance in a
                   device's MIB. It's the same as concatenating the type_oid and 
                   instance_id