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.
When is a check considered stale dated and what if the bank pays the item after that time period? The Uniform Commercial Code, section 4-404, has effectively eliminated the old concept of stale dates on checks. However, the status of a check does change somewhat once it is 6 months old. If a check that is more than 6 months old is presented to the paying bank for payment, the paying bank may refuse to pay it without being liable to its customer (the drawer of the check) for so refusing. It may also pay the check if it does so in good faith.