The following fill levels are considered normal for the corresponding age group (in accordance with leading auction houses and rarity dealers).

10 years and older                VTS/IN                (sometimes also referred to as BON, Base of Neck)
15 years and older                VTS     
20 years and older                TS       
30 years and older                HS                        (sometimes also referred to as Upper Shoulder or High Mid Shoulder; “between MS and TS”)
40 years and older                MS