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Scanning Problems


Scanning response sheets is feeding them through an optical mark reader and having the data from them successfully transferred to the application (see How OMR Scanning Works).

During scanning the following dialog shows the current status



It is important to remember that there are effectively four ways to feed a response through a scanner, face up vs face down and head first vs tail first. Three of these are likely to generate an error or lead to the response sheet being ignored.

Transferred data is verified with a number of checks. Failing any of these checks will cause an error message. These checks can be split into two groups.

Checks based on the underlying physicality of the response sheet
  • Incorrect Sheet Fed
  • Document No. Expected
  • Skew Error
  • Black Test Error
  • White Test Error

    Checks based on marks added to the response sheet during overprinting (or possibly incorrectly added by the person filling the form)
  • Invalid Front Overprint Alignment
  • Invalid Rear Overprint Alignment
  • Invalid Front Checksum
  • Invalid Rear Checksum
  • Incorrect Front Installation Number
  • Incorrect Rear Installation Number
  • Incorrect Front Questionnaire Number
  • Incorrect Rear Questionnaire Number
  • Unexpected Sheet Number
  • Duplicate Sheet Number
  • Unexpected Front Document Code
  • Unexpected Rear Document Code
  • Invalid Preprinted Front Checksum
  • Invalid Preprinted Rear Checksum

    All these checks occur sequentially in the order listed. If one check fails the remaining checks are not carried out.