Accidentals in parentheses

How should accidentals in parentheses be encoded?

• As accidental with parentheses: <accid accid="bs" enclose="paren"/> (current sibmei output)
• Accidental with square brackets: <accid accid="bs" enclose="brack"/>
• As editorial additions: <supplied><accid accid="bs"/></supplied>
• As editorial accidental: <accid accid="bs" func="edit"/>
• Combination of anything?

See as well rendered examples in Verovio Test Suite