specifies the fileref
assigned to be validated. In a DATA step, fileref can
be a character expression, a string enclosed in quotation marks, or
a DATA step variable whose value contains the fileref. In a macro, fileref can
be any expression.
Under UNIX, fileref can
also be a UNIX environment variable. The fileref or
the environment variable that you specify must be enclosed in double
quotation marks.
Details
A negative return code
indicates that the fileref exists, but the physical file associated
with the fileref does not exist. A positive value indicates that the
fileref is not assigned. A value of zero indicates that the fileref
and external file both exist.