Today I came across an odd symbol in Béla Bartók's Microkosmos.
The symbol occurs in Book 1, Score 21, Measure 8, at the end of a phrasing slur. It looks like a vertical bar that crosses only the first 2 topmost lines of the staff and it's unmetered.
My wild guess is that is a kind of very brief, unmetered rest similar to the breath mark in vocal music ...
What it is and how can I write it in Lilypond ?
PS: Yes caesura is also what I was thinking of but AFAIK is more of undetermined length rather than brief. And my guess (again :) is that the intent was for a brief separation between the expressions. Thanks for the replies :)