Partial inscription/mark

Partial inscription/mark, about 5 cm (2 in) in width, located in the lower-left corner of the painting. It resembles a horizontal oval and it has some partial vertical lines. It looks as if it has been partially removed in a previous conservation treatment. 
An attempt to digitally enhance the partial inscription/mark.

Roman emperor Domitian Oil painting Leonardo da Vinci Titian, Tizian, Tiziano Vecellio, Roman emperors, Eleven Caesars, Undici Cesari, Domitianus, Isabella d’Este, Federico II Gonzaga, Mantova, Mantua, Italy, Francis I, Amboise France, Charles I England.