1)Misinterpretation of the drawing for part marking
2)Drawing calls both detailed and assembly marking symbol.
3)That symbol is not visible clearly in the A4 size sheet.
4)It needs minimum 1:2 magnification in the soft copy of PDF file.
5)Inspector missed to bubble the detailed part marking symbol and marked to assembly symbol.
6)Operator marked as per the quality plan( bubble drawing)
7)Same is not picked in the final inspection.