appropriate way; typing in a 0 or using the space bar will clear a
filled square.
+Left-clicking a clue will mark it as done (grey it out), or unmark it
+if it is already marked. Holding Control or Shift and pressing an
+arrow key likewise marks any clue adjacent to the cursor in the given
+direction.
+
(All the actions described in \k{common-actions} are also available.)
\H{unequal-parameters} \I{parameters, for Unequal}Unequal parameters