Dependent Validation in SharePoint-synchronised list
 

I would like to apply dependent validation to a cell that forms part of a
SharePoint synchronised list. I got the validation working in a stand-alone
spreadsheet using this advice: http://www.contextures.com/xlDataVal02.html.
When I publish the list to my SharePoint site, the Excel validation rules
disappear. SharePoint allows some validation too - how can I recreate the
dependent validation in SharePoint?