I have a line engraved a few mm from the end of the swing arm, 4 mm on the left and 3mm on the right to be exact. Do all swing arms have lines engraved for alignment?

If i line the chain adjuster up with the very end of the swing arm im 1 mm out as far as this alleged engraved line.

Ive always aligned the rear with the line and the chain adjuster, and now im thinking maybe some one has just engraved these lines for whatever reason. i think i should be using the end of the swingarm and chain adjuster.
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If you measure from the centre of the swingarm spindle to the axle centre(on both sides)the wheel should be aligned.

There's various ways of ensuring correct chain alignment, and using the marks on the arm is not one of them!

I use a vernier gauge, others use string along the wheels, or rods which clamp to the rear sprocket and point down the chain line.
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