It can be enough of a problem finding the right one at the right moment among all those identification cards you carry in your wallet - but have you ever wondered how much more difficult things would be if they were all different shapes and sizes?

The standard format that allows us to slip them neatly in our wallets and use some of them, such as credit cards, worldwide did not fall out of the sky - it is the result of work by ISO (International Organization for Standardization) and IEC (International Electrotechnical Commission).

Identification cards are used for multiple purposes, from identifying customers and their bank accounts to providing access to buildings and parking lots. With the continued growth in international trade, travel and mobility of labour, identification cards must conform to identical sizes and dimensions for use in international interchange.

ISO/IEC 7810:2003, which replaces ISO/IEC 7810:1995, has been modified to include the card which is used extensively in the mobile telephone market (ID-000), to provide clarification on card opacity by clearly stating which parts of the card can and cannot be transparent, and by the addition of card resistance to heat.

"Manufacturers of cards and card readers are no longer targeting just national markets, they are looking at international markets to increase sales, standards help simplify this process," said the Convenor of the working group that developed the new standard.

"Larger production volumes also mean lower costs, another benefit of standardization. And at the end of it all, both the credit/debit card and other identification card users benefit from the flexibility of use provided by using identification cards based on ISO/IEC 7810."

The new standard specifies the physical characteristics of identification cards including card characteristics, and dimensions for four sizes of cards. It applies to all the different identification card technologies, from the magnetic stripe and optical card to contact/contactless integrated circuit (IC) card.

ISO/IEC 7810:2003 costs 67 Swiss francs and is available from ISO national member institutes (see the complete list with contact details) and from ISO Central Secretariat. The new standard is the work of ISO/IEC JTC 1, Information technology, subcommittee SC 17, Cards and personal identification, working group WG 1, Physical characteristics and test methods for ID-cards.