I see the examples of both your timeline and the Google Spreadsheet that generated it, but I still am unable to get Google Spreadsheets to accept a negative number as a date. I've tried downloading a new copy of the template from
Timeline.Verite.Co, but find that even a new spreadsheet does not accept the negative numbers.
Are there special formatting issues or document settings that need to happen on the Spreadsheet itself in order to get it to accept negative dates? Alternatively, is there a way I could get an editable copy of your spreadsheet with the negative numbers to use as the foundation for my timeline?
FYI, here's a link to my spreadsheet with indications that Google can't recognize the negative dates. Thanks for your help!