Unless I’m doing something wrong, my attempts to link from items in a Sheet to another file, a .rtf or .txt file, will not work at all.
This would go a long way toward making sheets more useful to me. I’d like to be able to associate an item of a record (or two) with another page of notes, for instance, but still be able to sort the collection of records and view the main dataset in a spreadsheet-like list.