Greek sources on the Khazar question are supported by an important document that the Daubmannus edition refers to as 'The Great Parchment.' According to this source, a Khazar legation was sent to the Byzantine Emperor Theophilus, and one of the envoys had the Khazars' history and topography tattooed on his body -- in the Khazar language, but using Hebrew letters.
// Dictionary of the Khazars, Milorad Pavic, 72-3
the defining feature of tattooing is that it is the making of indelible pigmented traces which are inside or underneath the skin ... behind what seems like a transparent layer ... The basic schema of tattooing is thus definable as the exteriorization of the interior which is simultaneously the interiorization of the exterior.
// Alfred Gell, Wrapping in Images: Tattooing in Polynesia (1993), found cited in Graffiti and the Writing Arts of Early Modern England, by Juliet Fleming