What I am calling layering has generated some controversy and I feel obligated to explain this situation. I interpret the issue is an objection some authors have to others commenting on their content without permission. The analogy that is often used is that an author can turn off comments but cannot stop those using an online annotation service from doing what amounts to the same thing. The concerns I have read have mostly addressed the linking of inappropriate comments, but to be fair any add-ons might be an issue with some critics. This capability is certainly present and some have taken steps to block annotation capabilities.
An interesting comparison might be made to the practice of users making use of ad blockers. An ad blocker modifies the display intended by the author and potentially deprives the author of revenue. The use of both ad blocking and layering are legal. I am more likely to defend layering because technically ALL of the content intended by the author is presented as created. In the case of layering, the viewer purposefully takes advantage of an opportunity to view and add content to the base display. The composite view is not forced on the viewer without the active viewer (you must turn the layering service on to see additions). Some may accept this distinction as meaningful and some may not.
I see one more factor that should be considered. To me, public and educational layering are different in one important way. Public layering allows commenting and viewing by anyone making use of the online layering service (should the service be activated). Educational layering makes use of added content that is shared within a known group to include the educator. While innapropriate additions are always possible, I see this concern an infrequent problem within educational settings. To my knowledge, there is no way for the author to allow educational, but not public layering.
Allow one more thought. The academic tradition in which I have spent my life allows criticism. I criticize published content all of the time. This short comment might be considered a criticism of the criticism of layering. The difference might be described as sequential versus integrated commenting. Taking issue with a position I link to or cite (say a research publication) would be sequential. Adding similar comments on top of the same content would be simultaneous. Of course, there are other differences, but the simultaneous comments have the advantage of precision and integration. The reader can see exactly what issue I am addressing and can contrast the positions taken in a very direct way. In addition, this can be a group process (pro and con) which would be more difficult, but not impossible to duplicate in a sequential way.
By the way, as an author I invite the layering of my content. With the Kindle books, this is allowed and encouraged whether this would be my position or not. As an author I have always found the content publicly highlighted in Kindle books I have worked on to be quite interesting. I would be curious regarding what others might say about my online content and would love to participate in related discussions if aware, but I welcome appropriate comments whether I am included or not.
I do think it would helpful if layering reached the level of popularity that some capabilities could be added to allow authors some degree of control. This would most likely be possible through the use of standards that allowed the inclusion of specific tags. The present system requires the inclusion of code that must recognize the specific layering system being applied and this seems very inefficient and beyond the expertise of many authors.
This content will be updated should I become aware of changes related to this issue