U.S. Pat.  No.  7,909,243 issued to Merkow et al.  disclose a system and method for completing a financial transaction using a wireless communication device such as a mobile telephone.  A transaction authorization request is sent from the device to an issuer using short message service.  An authentication message is sent from the issuer to the device, and a response is sent by a user of the device to confirm the identity of the user.  Once the identity of the user is verified, a surrogate account number, in a barcode format, is sent to the mobile communication device to be read by a point-of-sale device to complete the financial transaction.  A computer program product enabling the systems and methods described is also provided.  Preferably, the surrogate account number is unique to the particular transaction.  For example, adding an expiry date and time can make each surrogate account number unique. 
U.S. Pat.  No.  5,640,002 issued to Ruppert et al.  disclose a portable RFID tag and barcode reader that gathers information about items to be purchased etc.  by reading barcodes or RFID tags.  A store host computer gathers information about items to be purchased from the portable barcode/ID tag readers and then the items are bagged by the customer at the checkout stand or by employees of the store at the checkout stand or in a separate warehouse from which the customer picks up the order.  The portable barcode/RFID tag reader can also be used in authenticating articles by accessing a factory computer using a serial number for the article scanned from an RFID tag on the article. 
There is a need for methods and systems for use in transactions, and more specifically, to methods and systems employing time and/or location data for use in transactions such as decodable optical indicia having encoded time and location data for use in point-of-sale transactions.