ANSI/NISO Z39.56-1991 [SIC] is the only accredited standard for identifying serially published materials in a machine-readable context This standard is currently under revision. This is an unusual NISO standard in that it was envisioned for established formats but has been eclipsed by new developments in the industry that were barely imagined in the 1980s. [Article copies available from The Haworth Document Delivery Service: 1-800-342-9678.]