Because the document did not say to check the outer to see if it had a liner or not, the employee did not check, causing the NG workpiece to be mixed with the OK work.
Due to the document not telling us to check whether there is a lining on the outside, the employee did not check whether the NG workpiece is mixed properly with the work.
Because the document didn't tell Outer to check whether there was a Liner, the staff didn't check it, which made NG artifacts go smoothly with the work.