I would like to switch from one open document to another via the keyboard. Is this possible?
There might be a keyboard shortcut; I just don’t know. When working on two or more documents at the same time, I just open a separate window for each, sized not full screen, and position each of them so I can see part of each of them beside the one on top. Then I just click on whichever one I want to work on. The others remain behind, but still partly visible. It works for me and saves memorizing yet another shortcut. 
Hope this helps.
Through the ‘Window’ menu you can access all open documents.
Menu ‘Window’ has the first w underlined. You can press Alt+W (or Alt,W), then press the underlined character of the desired document name in the menu.
In this sample the sequence is Alt,W,U.
Note that the underlined character in the document name may vary when the list of documents vary.
More Help in Calling Menus With Shortcut Keys.
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