EXTRN            Define External                               MASM Directive

EXTRN     name:type,,,

Defines a variable, label, or symbol as external.  An external item is
one that is defined in another program module, but is used in the
program module containing the EXTRN directives.  There must be a
corresponding PUBLIC directive in the module that defines the item.

Notes:     The type of name must match the type originally used to
declare it in the external module. Legal types are BYTE,
WORD, DWORD, QWORD, TBYTE, NEAR, FAR, and ABS.

If the EXTRN directive is placed in a segment, the
external item is assumed to be in that segment.  The
item's PUBLIC directive in another module must also be
in the same segment.  If the EXTRN directive is not in
any segment, the corresponding PUBLIC directive can be
anywhere in the other module.

All characters in name are forced into upper-case when
writing the object file out.  Use of the MASM switches
/ML and /MX can be used to preserve lower-case.

The ABS type is used for symbols that represent absolute
numbers.

See also: PUBLIC
See also: BYTE
See also: WORD
See also: DWORD
See also: QWORD
See also: TBYTE
See also: NEAR
See also: FAR

EXTRN Define External