ANSI/NISO Z39.50 (=ISO 23950: "Information Retrieval (Z39.50): Application Service Definition and Protocol Specification") specifies a client/server-based protocol for
searching and retrieving information from remote databases.
The ONIX for Books Product Information Message is the
international standard for representing and communicating book
industry product information in electronic form.
ONIX for Serials is a family of XML formats for communicating
information about serial products and subscription information,
using the design principles and many of the elements defined in
ONIX for Books.
The EAD Document Type Definition (DTD) is a standard for encoding archival finding aids using Extensible Markup Language (XML). The standard is maintained in the Network Development and MARC Standards Office of the Library of Congress (LC) in partnership with the Society of American Archivists.