default response was changed from XML to JSON, and the 5000 queries per day limit was removed (although a limit of 2000 image lookups per days was introduced). On 1 November 2011, a major update to version 2 of the API was released. This new release dropped support for XML, data is always returned in JSON format, however the monthly data dumps of new data are only provided in XML format. On 1 February 2014, Discogs modified their API so that image requests will now require OAuth authorization, requiring each user of third-party applications to have a Discogs "application ID", with image requests now limited to 1,000 per day. Additionally the Premium API service was dropped. On 24 June 2014, Discogs deprecated their XML API in lieu of a JSON-formatted API. Discogs also allows full XML downloads of its Release, Artist, and Label data through the data.discogs.com subdomain. The recommendations API is not publicly available. Contribution system The data in Discogs comes from submissions contributed by users who have registered accounts on the site. The system has gone through four major revisions. Version One (V1) All incoming submissions were checked for formal and factual correctness by privileged users called "moderators", or "mods" for short, who had been selected by site management. Submissions and edits would not become visible or searchable until they received a single positive vote from a "mod". An even smaller pool of super-moderators called "editors" had the power to vote on proposed edits to artist and label data. Version Two (V2) This version introduced the concept of "submission limits" which prevented new users from submitting more than 2–3 releases for moderation. The number of possible submissions by a user increased on a logarithmic scale. The purpose of this was two-fold: 1) it helped keep the submission queue fairly small and manageable for moderators, and 2) it allowed the new user to acclimatise themselves slowly with the many formatting rules and guidelines of submitting to Discogs. Releases required a number of votes to be accepted into the database – initially the number of votes required was from four different moderators but in time the amount was decreased to three and then two. Version Three (V3) V3 launched in August 2007. Submission limits were eliminated, allowing each user to submit an unlimited number of updates and new entries. New releases added to the database were explicitly marked as "Unmoderated"