- feerate vs "fee rate" : so far we have always used "fee rate" (2 words). I would stick with this for consistency. Also it is better English as feerate is an invented term.
- you wrote "FREERATE" --> ha ha very funny, a Freudian slip, but sorry, it will not be free. ;) smiling
- uppercasing
- commas
- avoid extremes and hype, avoid "very" : very expensive --> expensive
- successfull -> ...ful (one L)
- sentence simplifications
- Onion vs onion, lowercase or uppercase, since this is not a product name it should be lowercase
- the example does not contain the information needed, added "forward" field in onion
- some part missing from a sentence
- etc
Expanded and rewrote large parts of this submission. I thought it would be more straightforward to break down a practical example and show readers exactly how a string of bits would be interpreted by another node.
I corrected an error from yesterday because I mistakenly did not realize that despite bit 2 not being used, bits 2 and 3 still form a "pair", so my count was off. One part I'm not 100% sure of is if I've read the string correctly. From right to left, I read bits 8 and 9 as "01", which is enabled and odd, so 'var_onion_optin' is enabled and backwards-compatible. Is this correct?
I think it's better to formally define ECDH in an earlier section in order to do justice to the concept. We may be able to lift some text from Mastering Bitcoin, as IIRC it covers stealth addresses in brief.