If you pass an argument BY VALUE, code the USING BY VALUE clause in the PROCEDURE DIVISION header of the subprogram. If you pass an argument BY REFERENCE or BY CONTENT, you do not need to indicate in the header how the argument was passed.
PROCEDURE DIVISION USING BY VALUE. . . PROCEDURE DIVISION USING. . . PROCEDURE DIVISION USING BY REFERENCE. . .
The first header above indicates that the data items are passed BY VALUE; the second or third headers indicate that the items are passed BY REFERENCE or BY CONTENT.
related references
The procedure division header (Enterprise COBOL Language Reference)
The USING phrase (Enterprise COBOL Language Reference)
CALL statement (Enterprise COBOL Language Reference)