Syntax:
pragma Common_Object (
     [Internal =>] LOCAL_NAME
  [, [External =>] EXTERNAL_SYMBOL]
  [, [Size     =>] EXTERNAL_SYMBOL] );
EXTERNAL_SYMBOL ::=
  IDENTIFIER
| static_string_EXPRESSION
This pragma enables the shared use of variables stored in overlaid
linker areas corresponding to the use of COMMON
in Fortran.  The single
object LOCAL_NAME is assigned to the area designated by
the External argument.
You may define a record to correspond to a series
of fields.  The Size argument
is syntax checked in GNAT, but otherwise ignored.
Common_Object is not supported on all platforms.  If no
support is available, then the code generator will issue a message
indicating that the necessary attribute for implementation of this
pragma is not available.