:) Probably "title page" or "chapter title page" would be a good choice. Although these are not everyday terms, they seem to fit with what you describe. With luck, some more knowledgeable person on here will jump in with an exact term :)

Hallo Michael, thank you for your answer! I wrote about a cover sheet (not a cover like a book cover, sorry for that), so it is a sheet of paper. It is not transparent but white with some additional information about the content of the chapter which follows this overlay sheet. And it is a chapter in a user manual (at least it's called "chapter" :D) which I try to translate.

I don't think there is any difference in the context you are using. I'm not sure that either exactly works for this usage, though: do you mean a protective, transparent page (or "leaf") bound into the book which protects a particular page (or chapter)? If the material used for the protective page is not transparent, this is just a "blank leaf", I think. If it is transparent, then it is a "transparent blank leaf". I'm not sure I fully understand your question, though, so let me set out what I think you mean. The word "chapter" is normally used, in this context, to describe a section of a book ( ein Kapitel?) An overlay is normally, in any graphics or book context, a transparent sheet or page that lines up with another sheet or page, and contains some additional elements of imagery or text. Calling this an "overlay sheet" is possible; the "sheet" element is unnecessary but not forbidden. (Überlagerung ? Auflage?) An overlay is not really a cover, which is something which protects what it contains. So, from lexico : A thing which lies on, over, or around something, especially in order to protect or conceal it. " So a book chapter would never have its own cover :( Do you mean something else by "chapter"? https://www.lexico.com/definition/overlay https://www.lexico.com/definition/cover

Hi, Well, the word "overlay" per se includes the meaning of a sheet or surface that covers something. So you may just use it alone to convey your meaning.