UDC revision and maintenance is the responsibility of the UDC Editorial Team. Changes to the schedules are based on a long term revision plan that can be traced through UDC documentation spanning many decades. In addition to this, a number of minor corrections and extensions are introduced annually following requests from users.

Revision and restructuring of an entire class can take between 2 to 10 years. During this period various versions and drafts are exchanged between subject specialists, the UDC Editorial Team and members of the UDC Advisory Board. The next step is to make a proposal available to the public in order to gather feedback from UDC users. This is achieved through publishing of the proposal in the Extensions & Corrections to the UDC (E&C). Upon collecting feedback the new class is introduced in the UDC MRF and published in the revised tables section of the following issue of the E&C.

Changes in the text, introduction of new classes or cancellations of classes are presented in the E&C following a well established convention. These amendments are also recorded in the administration fields of the UDC MRF and they are distributed as separate files to UDC licence holders. Cancelled classes and their redirections can be checked on our website.

UDC archive holds documentation of UDC changes that goes back to the beginning of the 20th century.