Linq and Fieldnames containing '_'

BIZ TMS Aurelius
2

I don't this it relates to the _ in field names, but to the fact that Art_nr is an association, not a primitive property. You should do something like this:

  adKanban.ObjectClass:=TKanban;
  adKanban.SetSourceList(dmMain.MainXDClient.List<TKanban>(
        CreateQuery.From(TKanban)
      .Filter(Linq['Art_nr.id']='f76db3be-8ae9-42e3-81f2-9ed116f4aa34')
      .QueryString
      ));
  adKanban.Open;

(note: the id property of TArt object was guessed, as you did not provide its mapping).