I was reading this blog entry about address-based identities versus card-based identities. I am still thinking about the contents and will post some more thoughts about that blog in the next few days. There was however one example in the blog I would like to comment on right away:

Whatsmore, both address-based identity and card-based identity can be further classified in some very helpful ways:

• Address-based identities can be broken into resolvable and non-resolvable. While an address-based identity is always unique in the address space in which it is assigned, that doesn’t necessarily mean it can be resolved, i.e., dereferenced via a mechanism or protocol that provides further discover or communications with a digital subject. An email address is a good example of the former; a browser cookie a good example of the latter.
• Card-based identities can be broken into addressable and non-addressable. This means that some card-based identities may contain an address-based identity and some may not. A business card is the classic example of an addressible card-based identity; in fact the primary purpose of most business cards is to share address-based identities. On the other hand a coffee-shop loyalty card is a good example of a non-addressable card-based identity: while it describes identity-related attributes of its owner (how many cups of coffee they have purchased), it may not contain any address-based identity whatsoever (not even your real-world name).

In the second bullet a coffee-shop loyalty card is used as an example of a card-based identity. That confuses me. Assuming, from the example, that the card does not contain any personal information like name or address, how can it be seen as a card-based identity? The only connection this loyalty card has with a person (identity) is that it is carried around by one. But that would make a lot of items suddenly card-based identities. The card cannot be used to identify or authenticate a person and has only value to the person carrying it around but it is in no way connected to that person. Following this reasoning, the 10 EURO note I am carrying around also is a card-based identity.