Thread:Andrewds1021/@comment-39340968-20200103003859/@comment-9605025-20200103011548

What do you mean by hidden? If you mean you want something that can be seen in the editor but not when viewing the page, you should be able to add comments in the markup.

Unfortunately, it seems that only source mode is capable of adding them and they will not be visible in VisualEditor (but they are visible in rich-text editor).

You make a comment like this: Visible Stuff

More Visible Stuff