Wonder whether those accents are part of Old Church Slavonic.

I have been browsing extensively the quite-remarkable pre-1917-Revolution
color-separation images, almost entirely of Russia, at the US Library of
Congress*, and did notice some religious inscriptions with lots of accents
above. I didn't try to download the typ. 39-MB TIFF-format images that are
available, but as I (hope to) continue to browse, I'll seriously consider
having a detailed look, and try to remember to post a link (even,
conceivably, an image) to Qalam.

*Googling on [prokudin] should be sufficient. There are now several sites
devoted to them, one looking like a labor of love, in Russian and English,
that provides a lot of info. about each image (but, iirc, no images of any
significant size).

Btw, one nicely-designed site, almost surely the LoC, shows the best of
the images, in a few major categories; some are very beautiful, and many
are interesting, some quite so. (I refer to such Web sites as "time
sinks". :) )

Best regards,

--
Nicholas Bodley /*|*\ Waltham, Mass. (Not "MA")
The curious hermit -- autodidact and polymath
whose father, Nikolai Aleksandrovich Bessarabov,
(="considered respelling") started life (as a Russian
Orthodox Xian.) in Voronezh. 1946: Cold War:
Use my mother's maiden name, whole family.