{                             }
    { dir-name                    }
    { { name IN } ... context-var }
    {                             }

    Specifies the name of a field or a record in a database by
    directory name, or by field or record name and context variable.
    A context variable is a temporary name you associate with a
    record. You define a context variable in a record selection
    expression (RSE). You specify a context variable only when you
    use the name IN parameter of the field or record expression
    syntax.

    For example, once you define E as the context variable for the
    EMPLOYEES relation, LAST_NAME IN E is a value expression that
    refers to a value from the LAST_NAME field of EMPLOYEES. Use name
    IN only in an expression with a context variable.