The IMPORT keyword specifies that storage for the data item being defined
is allocated in another module, but may be accessed in this module. The external_name
parameter, if specified, must be a character literal or constant.
If a name is defined as imported but no module in the program contains
an exported definition of the name, an error will occur at link time. See EXPORT{(external_name)}.
The IMPORT keyword on the definition specification is used to import data
items and cannot be used to import procedure names. Procedure names are imported
implicitly, to all modules in the program, when the EXPORT keyword is specified
on a procedure specification.
The following restrictions apply when IMPORT is specified:
The data item may not be initialized (the INZ keyword is not allowed).
The exporting module manages all initialization for the data.
An imported field cannot be defined as a compile-time or prerun-time array
or table, or as a data area. (Keywords CTDATA, FROMFILE, TOFILE, EXTFMT, PERRCD,
and DTAARA are not allowed.)
An imported field may not be specified as an argument to the RESET operation
code since the initial value is defined in the exporting module.
You cannot specify an imported field in the Result-Field entry of a PARM
in the *ENTRY PLIST.
You cannot define an imported field as based (the keyword BASED is not
allowed).
This keyword is not allowed for unnamed data structures.
The only other keywords allowed are DIM, EXTNAME, LIKE, OCCURS, and PREFIX.
The same external field name cannot be specified more than once per module
and also cannot be used as an external procedure name.
For a multiple-occurrence data structure or table, each module will contain
its own copy of the occurrence number or table index. An OCCUR or LOOKUP operation
in any module will have only a local impact since the occurrence number or
index is local to each module.