- (spanner-placement ,number? "The place of an annotation on a spanner.
-Note that this number must be between -1 and 1, with -1 representing the
-beginning of the spanner and 1 representing the end. The annotation will
-still be placed at the left or right extremity of the spanner, but this
-number ensures that when line breaking happens, the annotation is assigned
-to the correct broken piece and the footnote is put on the correct page.
-An important caveat is that this number applies to column ranks, not staff
-space. For example, 0 will place the annotation at the middle column of
-its parent's span, which may be to the right or left of the physical middle
-of the spanner.")
+ (spanner-broken ,boolean? "Indicates whether spanner
+alignment should be broken after the current spanner.")
+ (spanner-placement ,ly:dir? "The place of an annotation on a spanner.
+@code{LEFT} is for the first spanner, and @code{RIGHT} is for the last.
+@code{CENTER} will place it on the broken spanner that falls closest to the
+center of the length of the entire spanner, although this behavior is
+unpredictable in situations with lots of rhythmic diversity. For predictable
+results, use @code{LEFT} and @code{RIGHT}.")