In the Dewey Glossary at https://www.oclc.org/support/documentation/glossary/dewey.en.html I've found this: Reused number: A number with a total change in meaning from one edition to another. Usually numbers are reused only in complete revisions or when the reused number has been vacant for two consecutive editions. A common problem with reused number is the lack of edition information on assigned DDC numbers. I can only guess which DDC edition had been used when I stumble upon a DDC number in a catalog. I'd want a service too look up a number for the first edition it was introduced to, and possible removals and reuses. At least one should be able to tell whether a given number has ever been reused in the history of DDC. Build numbers will make this task even more complicated :-(

Can you tell whether updates within one edition only contain new numbers, additional notes, comments etc.? Or is it possible that an existing number is deleted or changes definition during the same edition of DDC? Putting the question another way: If I assigned a DDC number from DDC 23, do I need to consult after each update to make sure that the assigned number still exists with the same meaning like before the update?