Today I finished my first score with Dorico. I’m very satisfied how Dorico works.
I have only two remarks:
Some composers and some publishers use 8vb and 15mb instead of 8ba and 15ma bassa. It would be nice to have this also in notation options.
If 8va ends with a dotted note, the line of the 8va ends on the dot of the note (please look to the attached png). The dot is part of the note. Therefore the line should end after the dot.
Best, Maximilian
You can change all of the suffixes used on the Octave Lines page of Engraving Options.
We agree about this, and it’s on our list of things to fix up in future. You presumably spotted that you can drag the end of the octave line in Engrave mode to fix this manually for now.
Thank you for your answer, but I cannot find a possibility to change the suffixes from 8ba to 8vb or from 15ma to 15mb.
Only I can switch between ‘octave number’ and ‘octave number and suffix’ and between with suffix ‘bassa’ and without suffix ‘bassa’.
Referencing Elaine Gould’s book, page 28, I don’t see either 8vb or 15mb. (This actually surprised me since they are so universally understood). It would appear that the Dorico team is going for complete unambiguity in this area, which is admirable. However…
In Gould’s reference, however, I do see additional display options for octave lines below the staff, (no doubt representing what she considers common practice):
Interestingly, Dorico supports Gould’s suggested “15ma” by itself below the staff, but does not also include “8va” by itself below the staff.
Hopefully, some more options for Octave Lines can be added to the Engraving Options at some point in the future.
Ah, you’re quite right: we decided not to include these suffixes because they aren’t correct, even though they are quite commonly used in scores produced using other engraving software (they’re somewhat less common in music published before the rise of computer engraving). “8vb” is an unconventional abbreviation for “ottava bassa”; you can use “8ba” instead of “8va bassa”, but not “8vb”, I’m afraid. “15mb” is even more peculiar, as this is a very strange abbreviation for “quindicesima bassa”. I guess somewhere along the line somebody thought that the “a” at the end of “8va” was for “alta”, which means you can sort of justify replacing it with a “b” meaning “bassa”, but it’s not really correct. I’m somewhat against adding support for these incorrect suffixes, as I feel it’s perpetuating something a little bit nonsensical.
Daniel, quite a lot of work involves recreating, say, a missing viola part. I have to follow the conventions used elsewhere. I see where you’re coming from, but a copying gig is not often a teaching opportunity.
Daniel, thank you for your answer! It’s new for me that 8vb and 15mb is not correct. Until now I used this symbols in all my compositions.
But I guess the conventions have changed.
I’ve counted the ottava bassa’s in the scores I use this moment with my piano and composition students. So a random selection, but predominantly classical music of the 20th century.
The result: 4 times ‚8vb’ (publishers: Boosey, Hal Leonard, Wise, Donemus), 2 times ‚8b’ (Schott, Henry Lemoine), about 10 times ‚8’ (various publishers), about 20 scores didn’t use ottava bassa. But I didn’t find any ‚8ba’ or ‚8 bassa’ or ‚8va bassa’!
I think Dorico should be able to use also 8vb, but personally I will use in future probably one of the options, which is mentioned by Elaine Gould.
Daniel, a thought:
One approach to this issue might be to create two separate groups of octave lines in the clefs and octave lines panel (similar to how you have already approached clefs).
Availability of these ambiguous house style matched lines could appear something like:
Preferred Octave Lines (dropdown)
Other Octave Lines (dropdown) (or you could take the cheeky approach and go with “Ill-advised Octave Lines” 
… another area to encourage correct usage would be an additional category in the Engraving Options, e.g. along the lines of “Preferred Octave Labels” etc.
Another thought — are there plans at some point to open up the lists for the popovers to facilitate custom user edited libraries of clefs and octave lines, techniques etc?
If so, you could perhaps opt to include only the correct and unambiguous versions of these octave lines with Dorico, but if someone had the responsibility to match an existing house style (which is, unfortunately, all to frequently the case), they’d be able to engrave to any specification, needed improvements to the status quo aside.
I want to add that I so greatly appreciate the PAS compliant percussion notation you and your team brought to Sibelius, and at heart, I’m really with you on this attempt at standardization, too, but sadly, while I agree with you here in principal, from a pragmatic standpoint, I thought I should post these thoughts because of the type of work I am often asked to do.
I can’t help recalling the article “Tense Present” by the great David Foster Wallace, on the skullduggery involved with editing dictionaries (I think it’s the OED). Should you favor descriptive grammar, in which you just describe what people are actually doing? Or should you favor prescriptive grammar, in which you are a stickler for the rules? As DFW points out (at great length) this is a hard problem with no clear answers.
Dorico’s philosophy seems to be prescriptive at the outset, opening up to more descriptive usage as it matures, and this is totally reasonable imho. Robert’s proposal may be a nice way to navigate this treacherous path.
Custom libraries would be the solution to most of these things.