If the lug bore is offset or the lug does not have straight sides, the user can account for this by including the eccentricity in both axial or transverse directions and taper with alpha and beta angles.

Advanced Lug Geometry or “Lug Dimensional Scheme 
Proper lug design suggests that a lug never have negative alpha and beta angles simultaneously, but that alpha and beta angles be equivalent and opposite in sign or that the angles diverge such that the base widens as you move further from the bore. The figure titled “Lug Dimensional Scheme” shows axial (ecca) and transverse (ecct) eccentricity in the positive direction. If eccentricity is in the direction opposite the figure, the eccentricity value will be input as a negative value. Values for eccentricity and taper are not required unless the design has eccentricity or taper.

Eccentricity and Taper Input 
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