;;;
(when ,ly:moment? "Global time step associated with this column.")
(whiteout ,boolean-or-number? "If a number or true, the grob is
-printed over a white background that follows the outline of the stencil,
-if the grob is visible. A number sets the thickness of the outline as a
-multiple of the staff-line thickness. For compatibility with former
-behavior (now available with @code{whiteout-box}) the value @code{#t} is
-treated as @code{3.0}. Usually @code{#f} by default.")
- (whiteout-box ,boolean? "If true, the grob is printed over a
-rounded rectangular white background to white-out underlying material,
-if the grob is visible. Usually @code{#f} by default.")
+printed over a white background to white-out underlying material, if
+the grob is visible. A number indicates how far the white background
+extends beyond the bounding box of the grob as a multiple of the
+staff-line thickness. The shape of the background is determined by
+@code{whiteout-style}. Usually @code{#f} by default.")
+ (whiteout-style ,symbol? "Determines the shape of the
+@code{whiteout} background. Available are @code{'outline} and the
+default @code{'box}.")
(width ,ly:dimension? "The width of a grob measured in staff
space.")
(word-space ,ly:dimension? "Space to insert between words in