Make notes on information no longer present in current iteration, or that appeared in a different form in previous iterations, if considered to be important.
If the changes have been numerous, make a general statement.
Rules are given for each area, for example:
12.7B5.2b: Change in parallel title.
12.7B6.2b: Change in other title information.
12.7B7.2b: Change in statements of responsibility.
12.7B9.2b: Change in edition information.
12.7B11.2b: Change in place of publication or publisher.