"Keep track of durations in a run of grace notes."
'(columns common-shortest-duration))
+(ly:add-interface
+ 'key-cancellation-interface
+ "A key cancellation"
+ '())
+
(ly:add-interface
'ligature-interface
"A ligature"
'())
+(ly:add-interface
+ 'key-cancellation-interface
+ "A key cancellation"
+ '())
+
(ly:add-interface
'ligature-bracket-interface
"A bracket indicating a ligature in the original edition"