1  –  signal-arg

    Specifies a value expression. The specified value is converted to
    a CHARACTER(80) CHARACTER SET UNSPECIFIED string and returned
    as a secondary message to the client application. If the
    value expression converts to a character string longer than 80
    characters, it is truncated.

    You can use the sql_get_error_text routine to extract the signal-
    arg text in an application.

2  –  string-literal

    A quoted string literal which represents the SQLSTATE value.

3  –  value_expr

    Expects a character value expression which is used as the
    SQLSTATE status parameter. Any provided value expression is
    converted to a CHAR(5) value which is passed to SIGNAL.

    See Value Expressions for more information on value expressions.
    See SQLCA for more information about SQLSTATE.