A thumbnails page is generated for each segment in a captions file. In the header of such a page, property page.toprow is set to the value of property thumbs.toprow. As shown in usage above, this means that the page is topped with the standard dirbar followed by this file, which is a specialized title line.

On the left are buttons for the previous segment, the parent index page, and a slideshow. In the middle is the title, taken as all but the first two fields in the file: segment header. On  the right is a button to go to the next segment. From the end segments the empty pointer is replaced with an up pointer.