Frequency is measured in hertz (Hz). A person who has hearing within the normal range can hear sounds that have frequencies between 20 and 20,000 Hz. The most important sounds we hear every day are in the 250 to 6,000 Hz range.
An issue date was added, and cheques may not be valid a certain amount of time after issue. In the US and Canada a cheque is typically valid for six months after the date of issue, after which it is a stale-dated cheque, but this depends on where the cheque is drawn; in Australia this is typically fifteen months.
Stale- and Post-Dated Checks. The Accountholder shall date items drawn on an Account as of the day they are written. A stale-dated check is one that is dated six months or more before it is deposited or presented for payment. A post-dated check is one that is dated after the date it is deposited or presented for payment. The Bank may refuse to accept the deposit of stale- or post-dated checks, and it may refuse to honor such checks drawn against an Account.