/trends#node=6.b46is supposed to find http://www.hooktheory.com/theorytab/view/john-williams/the-imperial-march but it doesn’t. It also looks like supermode chords are simply ignored by Trends, even though the chords may not be supermodal when the Theorytab is shown in the relative major.
- Suspended chords are not supported at all, thus some inverted sus4 chords are regarded as identical to their no-suspension counterparts. Is this intentional?
- I expect the “Key” pulldown menu to allow searching chord progressions that use both the given chord and the exact key, but when I change the current key Trends gives me something like “undefined songs with G → em”. Are those keys simply for ease with searching key-independent chord progressions?
- Some placeholder characters appear for certain borrowed chords, for instance
node=D77also refers to the exact same borrowed chord but apparently they are treated as two chords having different spelling and function)
You’re right, TheoryTabs with supermode chords are currently ignored by trends. Trends stores data in the relative major mode, and there where issues where trends was being cluttered with several instances of chords that were technically enharmonically equivalent. Eventually we intend to upgrade the algorithm to group all chords enharmonically (we do this with some chords already, e.g., IV/IV = minor VII = mixolydian VII), but supermode songs represent a very small fraction of the database and so this hasn’t been on the top of our list.
The trends database strips suspensions and embellishments (such as add9) from chords. We did this because there weren’t enough suspended chords or add9 chords to cross the threshold of incidence to show up on the trends page. We also noticed that the function of chord progressions containing these chords is usually similar to their vanilla counterparts.
The Key pulldown transposes all songs into the selected key. Originally we didn’t have this option, but added it to ease searching for chord progressions for people not familiar with relative notation. The “undefined” is a bug, however, and we’ll look into that.
The letter is a reference to the mode; M is mixolydian and D is dorian. In this case, both the mixolydian and dorian VII7 are enharmonically equivalent (major 7 chords) so they were grouped together in the trends database.