12 Herbert J-M. Milne and Theodore C. Skeat, Scribes and Correctors of the Codex Sinaiticus (London, 1938), 71.
Milne & Skeat - p. 71
The occasional flaying-marks, i.e. accidental punctures in the skin, which develop into oval or circular holes in the process of manufacture, have as a rule been covered over with thin vellum shavings.