We have been supplying bendable copper clips in the shape of arrows for years, which can be used individually as line-by-line bookmarks or in multiples to refer to reading material. Here they come in three metals, which means they can also be used for color-coding purposes.
In diaries, for example, they can be used to distinguish between recurring and one-off appointments or to differentiate priorities. In notebooks, entries can be marked according to thematic contexts. And finally, they can also serve as bookmarks for several people in a book and prove to be useful aids in academic work - by distinguishing passages to be quoted, thoughts to be recorded for texts to be formulated and passages that require further research.