!rule-2147483902 false 2008-2009 Punch Mark Specifications 2008-2009 Punch Mark Specifications The pre-2010 specifications for punch marks state: (ii) Punch Marks The area of any such mark must not exceed 0.0044 square inches (2.84 The distance between adjacent punch marks (or between punch marks and grooves) must not be less than 0.168 inches (4.27 mm) measured from center to center. The depth of a punch mark must not exceed 0.040 inches (1.02 mm). Punch marks must not have sharp edges or raised lips (test on file). Punch marks are almost always circular in shape, and therefore the area of the punch mark can be determined using the calculation πr2 (where π =~3.142). The radius of the punch mark (circle) can be measured using the same magnifier that is used for measuring grooves (see Supplement A), as can the separation of two punch marks - measured center to center. The depth gauge used for measuring groove depths would not be suitable for measuring the depth of a punch mark. This measurement would require the use of a depth probe. While the depth of a punch mark is limited to 0.040 inches (1.02 mm) within the Rules, it is highly unlikely that this measurement would be requested in the field.