Which is correct, Caug7 or C7aug?

Both notations, C7aug and Caug7, are used to represent the same chord, which is a C augmented seventh chord. The “aug” in C7aug stands for “augmented,” indicating that the fifth of the chord (in this case, the G) is raised by a half step. The “7” in C7aug or Caug7 signifies that the chord also includes a minor seventh interval (in this case, the B♭).

The notation preference can vary depending on the context or personal preference of musicians. Both notations are commonly understood to represent the augmented seventh chord built on C.

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