Of course, the simple answer is relatively easy. Both drawings are checked for accuracy based on field observations in the field and comparing what is physically onsite. If the digital, hard copy, and field observations do not match, the design professional will be contacted requesting that an additional quality control/quality assurance check be made before the next submission. Below is an example of a request for a revision.
Although a minor error and was able to be corrected quickly by the design professional, this type of error was cause for a delay in both the closeout of the site and if not corrected, a delay in the issuance of the Certificate of Occupancy.