The open element represents the open symbol, which looks like a circle. The smufl attribute can be used to distinguish different SMuFL glyphs that have a similar appearance such as brassMuteOpen and guitarOpenPedal. If not present, the default glyph is brassMuteOpen.
The
<open>element.The open element represents the open symbol, which looks like a circle. The smufl attribute can be used to distinguish different SMuFL glyphs that have a similar appearance such as brassMuteOpen and guitarOpenPedal. If not present, the default glyph is brassMuteOpen.
See
https://www.w3.org/2021/06/musicxml40/musicxml-reference/elements/open/