INTEROPERABILITY

Given that numerous libraries around the world will be developing digitalcollections, how will it be possible for a user of library A to access and viewmaterial housed in library B? The existence of numerous digital libraries willmake it essential to share digitized items and ensure that cataloging,searching and retrieval tools at each one can be used readily with materialsfrom others.

Formats and Standards

While standards may have the effect of inhibiting innovation, they areessential to interoperability. Agreement must be achieved on such fundamentalissues as how text is to be stored. Is it straight ASCII, Microsoft Word, HTML,SGML, XML or something else? What kind of compression will be used? If text iscompressed, how will searching be done? How are images, music and videotape tobe represented? If agreement is not reached, at least the number of differentways in which works are digitized should be reduced to a number small enough toallow each library to support them.

Digital libraries must also have a second set of intake standards, going notto technology but to quality and reliability, which are discussed later on.Archivists question the permanence of digital materials since they note thatelectronic documents can be modified readily and the media on which they residebecome obsolete at least once each decade. The question then is how anever-expanding corpus of information will be converted to new media and formatsas these evolve.

Metadata

This term is often used to mean information about an item, ratherthan the information in the item itself. Examples include the author, title,date of acquisition, price paid, donor, etc. It is particularly critical tocapture metadata that is not present in or derivable from the item. Forexample, the author's date of birth is often not printed in a book but can beimportant in distinguishing among authors with similar names (particularlyparents and children). Libraries may "share" content by simply providing links,but uniform access to the content requires uniform metadata and a procedure forgenerating and storing it economically. It is of little avail to exchangedocuments at light speed if they must be held up for months until a humancataloger can prepare metadata.

Character Set Representations

This is not merely a question of different alphabets and writing systems, amajor hurdle in itself, but also an issue of how characters are represented.For example, there are several widely differing mappings of Chinese charactersinto ASCII. There is some appeal to having a worldwide universal standard, suchas Unicode, but the notion of attempting to list all of the world's glyphs andfreeze them in a standard reduces flexibility and tends to overlook obscure orvariant writing systems and restrict the development of new ones. Possibly astandard should be developed that permits new character sets so long as thedefinition of the glyphs and the representation mapping is maintained in anaccessible location.


Published: February 1999; WTECHyper-Librarian