How do I get updates to the DDC23 and Abridged 15?
The best source of updates is WebDewey, which incorporates all changes to the print editions, plus additional index terms and built numbers, and many other enhancements.
OCLC now offers a print-on-demand option if you prefer online access. The print-on-demand option will include the latest changes and topics available in the DDC and will be updated biannually, with releases occurring in January and July.
There is more information on WebDewey and how to get the printed version of Dewey Decimal Classification.