No I didn’t forget spell check, that’s the inscription on a monument at Shugborough Hall, Staffordshire. It’s never really been explained and so gathers curiosity even now.
The Shugborough Inscription is carved on the 18th Century monument, below a mirror image of a painting ‘Shepherds of Arcadia’ by painter Nicolas PoussÃn. The inscription became known more widely having been mentioned in a 1982 book, ‘The Holy Blood and The Holy Grail’.
The monument dates between 1748/63 and contained between the letters D and M sits an inscription OUOSVAVV. The letters DM are seen on Roman tombs, Diis Manibus which means “dedicated to the Shades”.
A google search will give you many offers for resolutions, perhaps it’s just a version of Grafitti or a secret message between one lover to another. This writer is happy to leave the code busting to others.