IUNSIGNED converts the expression x into an unsigned FIXED BINARY value without changing the bit pattern. If x is unsigned, the precision of the returned value is the same as that of x. If it is signed, the precision of the returned value is the same as that of x unless the precision of x is 7, 15, 31 or 63. In that case the precision of the returned signed FIXED BINARY is equal to that of x plus 1.