Hi again, Jonel.

Disclaimer: I'm sure you are aware of much of the following. I'm including detail, though, so that others who read this thread might find the information useful.

PG Music uses a system of scale reference that is based on comparing notes to the major scale. This is common throughout music instruction texts and teaching these days.

Based on this system, the notes of the major scale are given numbers 1 to 8 in Roman numerals. See the top row of the table in the image below.

When one looks at (say) the natural minor (see image), by comparison to the major scale, this has a flattened note III, flattened note VI and flattened note VII. The flat is written in front of the note number.

This then leads to the chords based on those notes being described in the same way.

Thus if I was entering chord III in C major, I enter III for the note it's based on. Since it's a minor chord, though, I need to add m as well. So chord III (in classical terms) is IIIm in BIAB nomenclature. This reads as, "the minor chord based on note III of the major scale."

If it's the chord based on note III in the minor scale, though, I'd enter it as bIII because the minor scale has a flattened note III when compared to the major scale. Since chord III in minor keys is a major chord, then in BIAB I would enter bIII because "major" is understood. In BIAB terminology, bIII reads as. "the major chord based on the flattened III note of the major scale." (See the footnote below about setting minor display.)

With this in mind, Bdim in C major would be...

VIIdim -- To get this to sound, though, it's necessary to set BIAB to play the diminished triad. By default, BIAB interprets Bdim as a standard 4 note diminished chord.

To make this setting, enter into Display Options and set "Treat dim as diminished triad".

Chantelle is correct in relation to classical harmony where borrowed chords are written using slashes. The most common is V/V (this particular chord is called the doppel dominant and in the key of C this is D7 - that is "the V chord of the major key that's based on note V of the C scale"). BIAB doesn't use this notation.


Some examples using BIAB's Roman numeral entry method...

Key G major: G-Em-Am-Am7-D7

I-VIm-IIm-IIm7-V7


Key D minor: Dm-C-Bb-A7

Im-bVII-bVI-V7


Explanation of D minor chords...

Im = minor chord based on note I of D major scale

bVII = major chord based on the flattened 7th note of the D major scale (keeping in mind the minor key is described in terms of the major scale and note VII is C# in D major but C natural in D minor).

bVI = major chord based on note bVI of the major scale.

V7 = seventh chord based on note V of the major scale.


NOTE: To get the above display in minor, it's necessary open Display Options and deactivate "for Roman Numerals for chords in minor keys, use relative major". If that is active, it's necessary to think of D minor in terms of F major.

Hope this helps.
Noel

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