Have to go with a copy/paste since this came from a pdf...

"A range check of realistic wind directions (0 to 360°) and wind speeds (< 40 m s-1) is also performed. This latter check may highlight realistic extreme winds; thus, WOCE-MET personnel visually verify all flags added by the automated quality control.

Visual inspection of the data, though time consuming, is essential. The analyst adds flags for spikes, known instrument malfunctions, discontinuities, and values that are highly inconsistent with the surrounding trend. This latter contingency requires knowledge of the behavior of wind data from vessels and is subjective. Automated tests for discontinuities and spikes are available (Vickers and Mahrt 1997), but we find visual inspection to be adequate. Based on 82 ship months of automated meteorological true winds, the two-level quality control applies flags to an average of 5% of wind speeds and 6% of wind directions. On some vessels, the visual inspection determines that all true wind directions and speeds are incorrect. Removing or correcting these flagged true wind values is essential before performing any application using the data.

The two-level quality control employed by WOCE-MET has proven invaluable. For two of the four vessels reporting all values necessary to compute true winds, the visual inspection allowed the analyst to determine that the platform wind direction was reported opposite the desired meteorological direction."

Unflagged sounds (based on the above) to be removal of flags from data proven to be correct. So if it is flagged because it may not appear to be accurate, unflagged means it has been verified correct, or not subject to any known model/scan bias.

Any mets want to correct this?