I’m trying to transpose a song for voice and piano down a half tone from E major to Eb major using the transpose window, but the only options I am given are ‘major’ or ‘diatonic’. I need to be able to select ‘minor’ as the interval choice, but it’s not showing.
In another song in C major I want to transpose to B major, but now I don’t get the option to transpose Key signatures either (it’s greyed out.)
Anyone have this issue?
In Dorico speak, E to Eb is a diminished unison. A minor second down from E would be D# - presumably with the selected passage that would result in accidentals that Dorico can’t figure out how to display.
Dorico can only transpose key signatures if they’re selected, and (among other things) they need to exist in order to be selected. My best guess is that you didn’t input a C major key signature at all. As far as Dorico’s concerned, if you haven’t added a key signature, your flow is atonal/open, not in C major.
Not only in Dorico-speak! In music theory in general, too.
The words “diminished unison” make my brain go booom 
But don’t forget that you can ask the dialog to calculate the interval for you on the right side. Just select E and E♭.
It’s technically an augmented unison downwards. I personally have never encountered a diminished unison and I don’t think such things as “negative intervals” really exist?
I think exactly the same way as you, klafkid. I have studied in Germany and it is the normal way to define this interval here. But I also learned, that in other countries a diminished unison is the common way to look at this. Therefore it would be nice, if Dorico would a bit more “open minded” and allow both ways …
I am also German trained.
It seems weird to me - is a minor third downwards equivalent a triple diminished unison?
But this is very offtopic…
… and it has been discussed more than once on this forum. 
Hi, thanks so much for your help. You’re right and for my C major song I forgot to specify C major as a key so once I did that I could transpose the C major song into B as I wanted.
And I’ve learned how to use the ‘calculate interval’ function (thanks Mark_Johnson) which my singer’s brain copes with much better, then Dorico does the heavy lifting and transposes the key changes within the song, which I believe was my problem in asking it to transpose from E to Eb (it calls that transposition a ‘diminished unison’) but it can’t apply that same transposition instruction to the sections in the song that are in Ab to G (I would need to specify ‘minor second down’.)
Thanks everybody who helped me here 
I completely agree! If we reversed the process, going from Eb up to E, we’d say moving UP an augmented unison, not a diminished unison. Intervals are a measure of distance, not direction.
I know I am shouting into the wind. That’s ok - I’m happy enough with Dorico to not let this bother me. Too much…
klafkid and HeiPet, its not just Germany. That’s the way I learned it too. (USA)
Finale also doesn’t know the “diminished unison.” To transpose, one either goes up or down an augmented unison.
My approach to understanding the naming of intervals is based on the appearance of the two notes involved. If they are on the same line or space as each other, then the interval is a unison (of one quality or another). If one note is on a line and the other is on an adjacent space (or vice versa), then the interval is a second (of one quality or another). Space to space or line to line will be a third, fifth, seventh, ninth, etc. In other words, the look of the interval determines the numerical part of its name.
The perfect intervals are unison, fourth, fifth and octave.
Flattening the upper note of a perfect interval results in a a diminished interval.
For example:
C to G is a perfect 5th, C to G♭ is a diminished 5th;
C to F is a perfect 4th, C to F♭ is a diminished 4th (sounds like a major 3rd, but looks like a 4th);
Lower C to upper C is a perfect octave, C to C♭ is a diminished octave (sounds like a major 7th, but looks like an octave);
C to the same C is a perfect unison, C to C♭ is a diminished unison.
This might not be the way that everybody was taught and understands it, but it seems to be the explanation. Perhaps the terminology used becomes somewhat ambiguous when the interval is being calculated downwards. If you are using the phrase “transpose by a diminished unison”, then you are going down a semitone. If the phrase is “transpose down by a diminished unison”, then it becomes less clear what is intended.
So which of them is the upper note here?
As intervals are typically calculated in an upward direction with the second note mentioned usually being the upper note, for the purposes of taking a consistent approach the second C can be considered as the upper note, even though it is the same pitch.
Maybe “Flattening the upper note of a perfect interval results in a diminished interval” can be reworded for special cases such as this to “Flattening the second note of a perfect interval results in a diminished interval”.
By the way, what is a “a triple finished unison”?
It was autocorrect- thanks for this, of course it should be a triple diminished unison.
I think you answered it yourself
Gb - C is still a diminished fifth, because one always goes from the lower to the higher pitch. I would argue, one does it AFTER the accidentals are applied (not before, as you suggested). In this case, it works for every interval, and diminished unisons go away.
I mean: why is Cb - C a diminished unison (remember: order doesn’t matter!) but C -C# an augmented unison?
As I see it, C - Fb and C# - F are both diminished fourths. Such is Cb - Fbb. Accidentals shouldn’t change the quality of interval.
Any type of G to any type of C (immediately above the G) has a visual distance of a 4th - line, space, line, space - 4 notes. The quality depends on the accidentals.
If intervals are calculated upwards by default (unless specified otherwise) C♭ to C is an augmented unison. C to C♭ is a diminished unison. For the purposes of being accurate, order does matter. Intervals are typically calculated as being from the first note to the second. C♭ to C is equivalent to C to C#. The two notes appear on the same line or space, so they are unisons. Removing the flat to make a natural sharpens the note the same as removing the implicit natural with a sharp. A sharp augments an interval, therefore it is an augmented unison.
I never specified that the C would be above the G, and this is an assumption you made with no ground.
If we talk absolute pitches, C-G is just a perfect fifth, as is G-C. Order doesn’t change the interval. Therefore C-Cb is the same interval as Cb-C (or C-C#).
If you insist on G-C being a fourth (thus not regarding absolute pitches), C - Cb has to be a diminished octave. (The complementary Interval to the augmented unison, just as the fourth is the complementary interval to the fifth.)
At this point I think it’s worth agreeing to disagree, though.
Flattening the second note of an (upward) octave interval results in a diminished octave. The same principle applied to a unison gives a diminished unison.
As I need to go to bed soon, I won’t continue this disussion at this point. I’ll read the Wikipedia article on intervals ( Interval (music) - Wikipedia ) and then retire for the night.
Wut? If the G is below the C, it’s a perfect fourth, not a perfect fifth. I suspect there’s also a language/translation issue here: “absolute pitches” doesn’t have any relevant meaning in English.