- "\n"
- "Some items need special treatment for line breaking. For example, a\n"
- "clef is normally only printed at the start of a line (i.e. after a\n"
- "line break). To model this, `breakable' items (clef, key signature,\n"
- "bar lines, etc.) are copied twice. Then we have three versions of each\n"
- "breakable item: one version if there is no line break, one version\n"
- "that is printed before the line break (at the end of a system), one\n"
- "version that is printed after the line break.\n"
- "\n"
- "Whether these versions are visible and take up space, is determined by\n"
- "the outcome of the @code{break-visibility}. This grob property is a\n"
- "function taking a direction (-1, 0 or 1) as argument. It returns a\n"
- "cons of booleans, signifying whether this grob should be transparent\n"
- "and have no extent.\n"
- "\n"
- "The following variables for break-visibility are predefined:\n"