I got it, I got it.
It is documented in the explanation for the 3rd parameter of the SpreadsheetDocument.Area() function, version with 4 number arguments.
A call like:
| Code |
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selection = SpreadsheetDocument.Area( , c1, r2, c2); |
selects the columns c1 to c2 (because first row is missing) from the formatting region that contains r2. That russian enghish was not very helpful though. I probably wouldn't understand what it means if I didn't know in advance what I was looking for.