In addition to the entities specified in 6.1.2,
the Global aspect may be specified for a subtype (including a formal
subtype), formal package, formal subprogram, and formal object of an
anonymous access-to-subprogram type.
The following additional syntax is provided to
override the mode of a formal parameter to reflect indirect effects on
variables reachable from the formal parameter by one or more access-value
The presence of the reserved word overriding
in a global mode indicates that the specification is overriding the mode
of a formal parameter with another mode to reflect the overall effect
of an invocation of the callable entity on the state associated with
the corresponding actual parameter.
The Global aspect for a subtype identifies the
global variables that might be referenced during default initialization,
adjustment as part of assignment, finalization of an object of the subtype,
or conversion to the subtype, including the evaluation of any assertion
expressions that apply. If not specified for the first subtype of a derived
type, the aspect defaults to that of the ancestor subtype; if not specified
for a nonderived composite first subtype the aspect defaults to that
of the enclosing library unit; if not specified for a nonderived elementary
first subtype (or scalar base subtype), the aspect defaults to null
in the absence of a predicate (or when the predicate is statically True),
and to that of the enclosing library unit otherwise. If not specified
for a nonfirst subtype S, the Global aspect defaults to that of
the subtype identified in the subtype_indication
The Global'Class aspect may be specified for the
first subtype of a tagged type T, indicating an upper bound on
the Global aspect of any descendant of T. If not specified, it
defaults to Unspecified.
For a tagged subtype T, each mode of its
Global aspect shall identify a subset of the variables identified either
by the corresponding mode, or by the in out mode, of the Global'Class
aspect of the first subtype of any ancestor of T.