This is the same amount of fu points as a closed pinfu won by ron (but that would only be 30 fu 1 han).
It seems like the open pinfu gets the 10 fu (after rounding) for menzen ron even though it is not menzen.
After consulting with two people smarter than me, I have learned the following:
Ignatius had stated: "It's true that a valueless hand, as an open hand made with only sequences, has no han value, and it will be a 30 Fu hand. But I would like to know what happens if you have a hand like that, and 2 or more han.
Is it still 30 Fu?, or as there are 2 or more han, and the hand is valueless, will it become a 20 Fu hand?"
Bart stated: "Any open hand that meets the other three requirements of Pinfu and is won by Ron will always get the 30 Fu regardless of the Yaku.
Certainly you will need one proper Yaku since the Pinfu doesn't count, for example Tanyao (if Kuitan rule applied) or a straight, outside hand, full flush or even a half-flush with four same-suit chows and a non-scoring wind pair!"
So, based on the above, I made up an example to illustrate.
Suppose you had an open full flush where you won by ron on a double-sided wait.
This is 5 han and has to be 30 fu because there are NO 20 FU RON WIN VALUES in the scoring tables.














I'm not crazy about this since I've not seen it written anywhere and the computer always did the scoring for me but now that I've been teaching people to play riichi with me, I need to be prepared with some logical answers.
I can see now why section 6.3 in the rules (just posted) awards 2 fu for an open pinfu. (still don't like the words "open pinfu", seems like a contradiction)
But why should it be impossible to have a 20 fu 5 han ron win? (or any amount of han greater than 1)