To generate **Isochrone zoning**, the route calculator must be set to Fastest. To generate **Isodistance zoning**, the route calculator must be set to Shortest.
The Tags field can contain up to a maximum of 255 characters. If the tag or list of tags is over that limit, this error is displayed. To prevent this error occurring, check the Tags column to make sure this cell contains fewer than 255 characters.
For night hours, from 11pm to 7am, for example, the file must contain a column with the next day’s timetable (7am in the example). The “timetable end” column must contain the formula **=next day timetable cell+ 24:00:00**. Cells must be in the format Time -> 13:37:46 |cell_format|.
The spreadsheet structure is corrupted. Column headers are offset relative to their content, for example. Opening the csv file in a text editor can help you identify the mis-match.
When you click on the field to edit, instructions appear in a popover. They might, for example, tell you how to format the data. :numref:`explanation_window_colum_lists`
cynthia