Faint lines on a manuscript page may belong to its preparation rather than to a later reader’s markings. Looking for them changes the page from a surface of words into a planned space.
Start with an explained example
Getty’s guide to a medieval manuscript page points out ruling beneath two columns of text. The specific example is a fifteenth-century Bible, useful for learning an observation method rather than for generalising about all historical religious books.
Follow a line across the page image where resolution allows. Compare its position with the writing without claiming a tool or production sequence the source does not establish.
Ask how the space is organised
Notice margins, column boundaries and areas occupied by decoration. A page can be carefully prepared even when individual letters vary or a line of text finishes unevenly.
In your notebook, separate a visible line from a catalogue’s interpretation of it as ruling. If the image is too small, record that limit. This approach gives material evidence a place alongside translation and interpretation, while keeping the historical example attached to the period and object that actually support it.