-@code{space} -- the vertical distance, measured in staff-spaces,
-between the @emph{reference points} of the two items, when no
-collisions would result, and no stretching or compressing is in
-effect. The reference point of a (title or top-level) markup is
-its highest point, and the reference point of a system is the
-vertical center of the nearest @code{StaffSymbol} -- even if a
-non-staff line (such as a @code{Lyrics} context) is in the way.
-Values for @code{space} that are less than either @code{padding}
-or @code{minimum-distance} are not meaningful, since the resulting
-distance will never be less than either @code{padding} or
-@code{minimum-distance}.
+@code{basic-distance} -- the vertical distance, measured in
+staff-spaces, between the @emph{reference points} of the two
+items, when no collisions would result, and no stretching or
+compressing is in effect. The reference point of a (title or
+top-level) markup is its highest point, and the reference point of
+a system is the vertical center of the nearest @code{StaffSymbol}
+-- even if a non-staff line (such as a @code{Lyrics} context) is
+in the way. Values for @code{basic-distance} that are less than
+either @code{padding} or @code{minimum-distance} are not
+meaningful, since the resulting distance will never be less than
+either @code{padding} or @code{minimum-distance}.