we should perhaps recognise that a lot of what exists in WHC documentation is inaccurate and illogical
Well, I guess that in the eighties and nineties the WHC was less formalistic/thorough than it has become in the meantime...
I think it makes sense to quote the full decision minutes of the WHC in the case of Schokland, as the 20th century aspect is not the only one highlighted:The Committee decided to inscribe this site on the basis of criteria (iii) and (v), considering that Schokland and its surroundings preserve the last surviving evidence of a prehistoric and early historic society that had adapted to the precarious life of wetland setlements under the constant threat of temporary or permanent incursions by the sea. Schokland is included in the agricultural landscape created by the reclamation of the former Zuyder Zee, part of the never-ceasing struggle of the people of the Netherlands against water, and one of the greatest and most visionary human achievements of the twentieth century.
The "prehistoric and early historic" elements of Schokland are clearly mentioned first (even though no specific century is named). Only thereafter does it state that nowadays Schokland is included within the visionary achievement of the Noordoostpolder - which sounds more like a description of location rather than a description of the site itself (e.g. similar to stating that the Tower of London is located close to the visionary works of 21st century bank architecture of the City of London). Correct me if I'm wrong, but it seems to me that Schokland itself - from the descriptions I can find of it - does not really include any 20th century structures (apart from the part of the polder included within the boundaries of the site - but are those parts actually representative of the Noordoostpolder itself?).
On the WHC website, the "Brief Description" and the "Long Description" do highlight much more the ancient (i.e. pre 20th century) aspects of Schokland. (BTW: does anyone know what value these Brief and Long descriptions have? As they're on the WHC website, they have an official stamp of approval, however they do not seem to quote the original decision minutes...).
Sorry to focus so much on this Schokland issue - ultimately I'm indifferent how it is classified, but for me it's a case-study in how/whether to use WHC official documentation for purposes for which it was not originally intended (ie. create a timeline of WHC sites).
In a nutshell, I agree with Solivagant and wonder whether instead of basing our decisions solely on whatever official documents there may be we should also make use - where necessary - of other external sources to make our own judgement of a site's value...