Many GFDL violations occur when GFDL corpus access providers fail to provide links to source materials. The licence requires users to "Preserve the network location, if any, given in the Document" if it is in fact given in the document, not in associated text added by a service.
When they republish GFDL text that has been published by other providers, such as Wikipedia, the largest and best known source of GFDL content on the net, some providers omit the link to the location where it can be edited, corrected or otherwise fixed.
Other types of GFDL violations include:
- failing to credit the top five contributors when a document is exported via XML - this is quite difficult to do without an interwiki identity standard
- failing to permit retrieval of any page's source text, even to trolls
- failing to respect the status of Secondary Sections and Invariant Sections or respect the obligations implied by the latter
Wikipedia has complicated matters with its policy of forcing other GFDL corpus access providers to provide links to itself if any text is similar to any other GFDL text that has been published via Wikipedia (which legally and technically is only a user interface). While it is the largest and best known source, it is deliberately NOT the authoratitive or most quotable source for any particular topic. Accordingly it is seriously detrimental to the GFDL corpus to have all links on all topics lead to Wikipedia. The license implies that the best and most authoritative version be linked to, not just the first place where the material appeared.