User:Vector/Vector's chord names
all interval qualities "cascade" to any following intervals until another quality is specified. (Major and minor fifths and fourths both evaluate to perfect, and if "perfect" is specified then it does not cascade and major or minor must be specified for following intervals. Note that perfect is assumed for fourths and fifths and does not need to be explicitly specified unless it is the first character of the chord name after the note or degree name - that is, C11 should be CP11, in order to avoid A11 being ambiguous between "A perfect 11" and "augmented 11") Then, the final note in the chain of thirds (if not already specified), then any additions and alterations (which are always specified with interval qualities, not accidentals, and can always be recognized by the breaking of the chain of thirds. By default, alterations or additions that specify a scale degree that already exists in the chord are alterations, and this is where we bring the "+" symbol back which can be used to clarify that it's an addition. (as in, Cmd5 is C - E - Gb, while Cm+d5 is C - E - Gb - G.) (Note that default additions cannot be validly read as alterations.) Chords are always assumed to be triads by default. Degrees can be omitted by using the "-" symbol: CMm7-5 is a C dominant 7th chord without a 5th (so C - E - Bb). - can be treated like an interval quality, with the caveat that it only applies to a single degree and does not "cascade". So, "C-" just means a C chord without a 3rd, not without both a 3rd and a 5th. "C--5" would be a C chord without a third or fifth, aka just a single C note lol. Otherwise, specifying a degree without a quality is invalid (so "C" would be an invalid chord name, it has to be "CM"). Note that the very first specification is assumed to apply to the third, and to cascade to other intervals unless it's a "-", so a "3" isn't necessary (and should be avoided unless replacing the third like in a Cd7m3 chord). "Cd7" is taken to mean a chord that diminishes all intervals and stacks thirds up to the seventh (so C Ebb Gb Bbb). A chord that diminishes only the seventh should be CMd7 or Cmd7, depending on the quality of your third.
This system works with essentially any system of qualities, but for clarity multi-symbol qualities (i.e. "2A" for double-augmented, "sA" for semiaugmented, or even interval-size-based ones like "sM" for submajor) should be enclosed in parentheses.
