Can I add custom notations to a MusicXML file? For example, I want to add specific notations for "downstroke" and "upstroke" used in the Turkish musical instruments baglama and saz. These are unique notations for these instruments, similar to how some Chinese instruments have their own unique notations. How can I achieve this? How do people handle this kind of situation for instruments with unique notations?
This is current situation.
