The REDDIS REGIS CELLIS ARCIS components on this “tombstone” were first referred to by Noël Corbu in 1962 on a Frances-Inter radio programme. The “tombstone” was later revised by Philippe de Chérisey during the mid-1960s as part of his puzzle for his “large parchment”, wrongly ascribed to Eugène Stüblein (there is no evidence that Stüblein had any secondary interest in engraved tombstones of the Languedoc) – see:
‘Priory of Sion: The ‘Et In Arcadia Ego’ Tombstone’