The International Standard Authority Data Number (ISADN) was a registry proposed by the International Federation of Library Associations and Institutions (IFLA) to provide and maintain unique identifiers for entities described in authority data.
[1] Francoise Bourdon was a major proponent of such a standard, proposing a structure for the ISADN and recommending that the number uniquely identify authority records, rather than their subjects.
[2] A 1989 article by Delsey described the work on the IFLA Working Group on an International Authority System, spending a good portion of time on conceptualizing an international standard number "that will facilitate the linkage of variant authorities for the same identity."
[4] Tillett suggested that the cluster identifiers used by the Virtual International Authority File might meet the needs expressed in the proposal.
[1] The concept of an ISADN continues to be relevant to the information science community, as it could be a great help in the problem of measuring an individual author's research output.