This option, on the Company screen, Options tab, allows the Tester during Calibration to override the "Keep On Schedule" set on the master record.

Example - A master record is set with a Frequency of 1 Year, Last Cal Date is '01-Feb-2020', Next Cal Date is set to '01-Feb-2021 and the Keep On Schedule checkbox is checked.

A Passing Calibration entered on 09-Feb-2021 will roll the Next Cal Date to "01-Feb-2022"

Unchecking the "Keep On Schedule (Override Manually)" will Now roll the Next Cal Date to "09-Feb-2022"