Next time the Internet comes crashing down about your ears, spare a thought for the value of standards, starting with TCP/IP and HTTP. When you consider how the superhighway relies on precise implementation of an immense jigsaw of protocols and standards, it’s a miracle we ever find anything. But while we can’t get along without them, standards are also a pain. They push you into one-size-fits-all and clip the wings of dizzy free-fliers.
At ISKO-UK’s Great Debate  last February, the international standard ISO 25964  collected a lot of flak from some speakers who wanted their thesauri to escape control, and conversely from others who urged greater discipline, in the style of an ontology. So it was refreshing to attend EDUG’s April workshop , where the ISO 25964 guidance on mapping received a grateful welcome.
EDUG is the European Dewey User Group, whose membership includes a great many national libraries and major university libraries. Their patrons want unfettered and uncluttered access, not just to the resources held locally, but to all the collections you can reach through the Internet. Given the multiplicity of different thesauri, subject headings and classification schemes used to index and/or classify the original material, and given the shrinking budgets for re-classifying new acquisitions, mappings between the various vocabularies have been seen as part of the solution.
But mappings are a challenge! Between one thesaurus and another, cases of exact equivalence between concepts are the exception not the rule. Between a thesaurus and a classification scheme there’s an additional complication – the precoordination built into most classes. Thesaurus concepts designed for postcoordinate indexing do not easily map to or from classmarks, originally developed for arranging books on shelves.
While mapping has no easy answers, that does not mean we should give up trying. As Grete Seland quoted from Piet Hein:
Problems worthy of attack
Prove their worth by hitting back.
ISO 25964 sets out basic guidelines, starting with thesauri and reaching part of the way towards classification schemes and other types of Knowledge Organization System (KOS). For some years members of EDUG have been drawing upon these guidelines in projects such as MACS , Criss-Cross , Coli-conc , and a project to map the Norwegian thesaurus Humord to Dewey. Some are looking towards Semantic Web applications; others are simply trying to speed up cataloguing of resources already classified or indexed by a different KOS. In the EDUG forum a big concern is to build all the accumulated knowledge guidance into WebDewey .
This workshop in Naples focused specifically on developing recommendations for best practice when mapping to the Dewey Decimal Classification System. Standards were greatly in demand. Speakers pointed out the limitations of both ISO 25964 and SKOS  in this context, but the general conclusion was to build on and extend these standards rather than casting them aside. Detailed conclusions of the four working groups are currently in discussion, and should be published on the website  by the end of June 2015.
So come back standards, all is forgiven… for the meantime. And as for the teams developing mappings to Dewey, even when supported by standards, wish them fortitude and a jar of paracetamol as they grapple with the intellectual challenges of mapping to a pre-coordinated scheme.