I've just encountered an annoying hassle where proper handling of archival bibliographic data requires keeping track of leading zeros in ID numbers; and these seem like informed groups to ask if anyone has comments or observations on other electronic or online systems that require or even allow leading zeros?
Specifically the Am Phys Soc now identifies articles not by volume and page numbers but by volume and a six-digit "article number" which sometimes does and sometimes does not have an initial zero -- but if it does you _must_ keep it for various bibliographic and online citations to work properly. A few quick tests show that the default behavior is to automatically and irretrievably discard leading zeros on integer numbers keyed into an Excel worksheet cell or a Mathematic list. One of my bank accounts prints my account number with three leading zeros, but won't accept them in the Account Number field for online login. On the other hand for another ID card I have, you _must_ type the leading zeros.
Are there any kind of published refs or computer standards or human interface guidelines on the use of leading zeros? ZIP codes use 'em, phone numbers don't?