@Piet_Strydom answered it, but here’s some additional information.
Think of the whole situation as this.
In Coda, all data can belong in two places: in tables or on the canvas.
As of Feb 2021, you cannot reference data from the canvas (i.e. you cannot reference the text that you type in a page). Maybe Coda adds this capability in the future. At the moment, you can only reference data from tables.
(small addition: each page has an ID, each object has an ID, and each line has an ID too, so you can link to them in a URL. Yet it still won’t let you actually read the contents of that page/object/line)
Views are tables.
Canvas controls (buttons, checkboxes, selects etc) are also tables Those are hidden “Global” tables that you cannot read directly from, but you can reference controls by the names you give them.
Canvas formulas are also tables, but again, you cannot reference those tables directly. You can only reference them by formula name (named formulas only, obviously)
And yeah, when I say “canvas control”, “canvas formula”, “data on canvas”, I mean a control, a formula, and any text that is placed directly in a page outside of any view or table.
Canvas formulas / canvas button formulas don’t have
thisRow reference because logically there’s no table or row those are placed in* (technically there is and you can use them but the results will be undefined)
Oh, and also when I say “canvas” I mean collectively all pages. It doesn’t matter which page an item is placed in — it’s purely visual matter that the doc’s canvas is split into pages and you choose to place certain items visually closer to each other