All managed object definitions have to have
a mandatory part. The mandatory part has to contain a DERIVED FROM
clause or a CHARACTERIZED BY clause or both. In the example both
are present.
The mandatory part of all managed object
contains a DERIVED FROM clause which is present in all managed
object definitions that ISO/ITU-T
have defined except top. The managed object top is a special class
from which all other managed objects are ultimately derived.
In this example, the forumTestObject
is derived directly from top.
Notice that since top is defined
in another document, the reference to top must be preceded by the name of
the document, i.e:
"Rec. X.721 | ISO/IEC 101652 : 1992":top
In addition to the definition that are inherited
from top, the forumTestObject has mandatory components
that are defined by the CHARACTERIZED BY clause. This definition is
in a package called forumTestObjectPkg (see Package
example).
The condition
attached to each PRESENT IF clause defines the circumstances in
which the package will be present in a managed object instance. The !
an instance supports it ! is the standard form of words that
indicates that the package is optional, i.e. it is not dependent on any
aspects of the managed object.
