I was reading the indictment of Paul J. Manafort, as published by The New York Times, and I got stuck on a sentence starting with
From in or about and between 2006 and 2017 [...]
I understand that the starting date here is not certain, and could be before or after 2006, but I can think of many more straightforward1 ways to say that, like “from around 2006, to 2017”.
I'd like to understand a) how to unfold that sentence grammatically, and b) what the reasons are for using this particular construct.
1 For me as a non native speaker, at least.