On Wikipedia it says:

Some of the symbols used for chord quality are similar to those used for interval quality:

    m, or min for minor,
    M, maj, or no symbol (see rule 2 below) for major,
    aug for augmented,
    dim for diminished.

In addition, however,

    Δ is sometimes used for major,[a] instead of the standard M, or maj,
    − is sometimes used for minor, instead of the standard m or min,
    +, or aug, is used for augmented (A is not used),
    o, °, dim, is used for diminished (d is not used),
    ø, or Ø is used for half diminished,
    dom is used for dominant.

Is it just tradition or is there a good reason why A and d are not used for augmented and diminished?

  • 10
    Mainly because A and D are used for chord names; it would be confusing to use them to describe the quality of the chord as well Apr 15 '15 at 8:58
  • If that is the only reason, I use it. (I am programming something.)
    – user19822
    Apr 15 '15 at 10:56
  • 5
    If you are programming something where you expect users to type the an identifier for a chord, please do not us A or D, as these letters will then have two meanings, depending on context. It will be difficult to parse the instruction and difficult to write it, too.
    – AJFaraday
    Apr 15 '15 at 14:40
  • 2
    I'm not sure what the problem is with those characters as you can look for and display the + and ° characters in pretty much any language.
    – Dom
    Apr 15 '15 at 18:19
  • 2
    "Not too confusing" seems like poor reason to buck convention. Might as well call your notes A-L instead of having sharps and flats.
    – user28
    Apr 15 '15 at 21:14

M cannot be confused with the letter name of a note, whereas D and A can. The + is probably due to the interval (usually 5th) being larger than original by a semitone. That being the case, dim could be -, but that is sometimes used to denote minor , NNS uses it. Why o, not a clue! There isn't even an o in the word!


Others mentioned the possible confusion with note names. And indeed, in some German songbooks (like the 1909 "Zupfgeigenhansel") you might find Cv instead of Cdim (v for vermindert), with v not being in competition with a note name.

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