The following three ABC code samples should be equivalent:

X:0         X:0            X:0
K:C bass    K:Cmaj bass    K:C major bass
A,,B,,C,    A,,B,,C,       A,,B,,C,

However, the first image displays incorrectly if it has been previously displayed and cached by the browser.

To reproduce, if the image immediately below looks correct, reload the page, and it produces the image at the bottom of this post.

X:0
K:C bass
A,,B,,C,

Whereas the other two both render correctly regardless whether they were previously cached, as follows.

X:0
K:C major bass
A,,B,,C,

The incorrect image looks like this.

Reproduced on

Widows 10 (v. 2004) with

• Chrome 85.0.4183.121 (on 2 machines)
• Edge 85.0.564.63
• Firefox 81.0 (on 2 machines; clean install. Behavior is different, however. First time opening page, display incorrect. Okay on refresh.)

MacOS 10.15.7 with

• Chrome 85.0.4183.121
• Safari 14.0