What's the standard notation for the occurrence of the same pitch played on two different strings of the same instrument simultaneously, to be used within the same staff?
The typical context would be a double stop lick that needs to resolve in unison, perhaps on the tonic. The reason for playing the same note on two strings rather than one might be uniform volume across the lick or just the special quality of the sound. It might be quite inconvenient to split the entire double stop lick into two separate staves just to avoid the local issue of notation.
I understand that I could just write "On D and G" above a G note (if using English), but I wonder whether there's any established culture neutral notation as an alternative to that. I don't care whether the individual strings are notated explicitly, or just the "doublestopness".