Hi,
First column has to hold the value TRAIN, VALIDATE, TEST or UNASSIGNED.
The second column if the GCS path of your image.
The third column is the label of your image.
The remaining columns hold the bounding box in either of the two formats:
-(x_relative_min, y_relative_min,,,x_relative_max,y_relative_max,,)
-(x_relative_min,y_relative_min,x_relative_max,y_relative_min,x_relative_max,y_relative_max,x_relative_min,y_relative_max)
As displayed in the first format of the bounding box, even if a column is empty, you still have to include a comma with nothing indicated after it. In other words, each row is required to have 11 columns even if some columns for some rows are empty for the upload to properly work.