( ( ( ( ( ( ( ( fig insertion of keys to these pictures make the third property of -trees particularly obviousall terminal nodes appear on the same level one is therefore inclined to compare these structures with garden hedges that have been recently trimmed with hedge scissors the algorithm for the construction of sbb-trees is show below it is based on definition of the type node with the two components lh and rhindicating whether or not the left and right pointers are horizontal type node record keycountintegerleftrightpointer to nodelhrhboolean end the recursive procedure search again follows the pattern of the basic binary tree insertion algorithm third parameter is addedit indicates whether or not the subtree with root has changedand it corresponds directly to the parameter of the -tree search program we must notehoweverthe consequence of representing pages as linked listsa page is traversed by either one or two calls of the search procedure we must distinguish between the case of subtree (indicated by vertical pointerthat has grown and sibling node (indicated by horizontal pointerthat has obtained another sibling and hence requires page split the problem is easily solved by introducing three-valued with the following meanings