What's in a name, what's in a number: some characteristics of identifiers on electronic networks

Identifiers on electronic networks such as telephone numbers, domain names, IP-addresses and e-mail addresses are not only necessary components of information and communication technology (ICT) applications, but they have also become a new kind of information good that can be traded separately. Identifiers on electronic networks cannot be treated with standard information goods theory; they have very different economic and technical characteristics. The main characteristics are excludability, network externalities and the lack of scale advantages in the daily operations of an identifier system. The excludability of identifiers has brought extensive public debate on ownership questions, especially for mnemonic identifiers that resemble trademark names. Network externality effects and the technical remedies to reduce operational scaling disadvantages as much as possible, have resulted in the appearance of centralised co-ordination or monopolistic control of identifier systems and as a consequence a series of governance questions. A survey on various existing identifier systems is presented after an introduction on the economic and technical characteristics of identifiers. The survey shows a large variety of institutional arrangements and market structures for assigning identifiers on electronic networks. Data analysis of Domain Name registration statistics show substantial effects of policy reform on the growth in registered Domain Names.