"Title: Splitting the subtree\n\
\n\
When a nodes is linked to more than one page\n\
and one of the instances is changed there is\n\
a choice to be made.  Should the changes effect\n\
only the copy actually modified or should they be\n\
global to all instances of the node?  If the changes\n\
are to be local, then the subtree is split so that\n\
there are two copies of the node, one with the new\n\
values on the current page and the old copy which remains\n\
unchanged.\n\
\n\
For example, given that node C occurs in both pages A and B\n\
in the drawing below and the copy if drawing A is modified,\n\
the following two cases can occur.\n\
\n\
  A     B                          A    B\n\
   \\   /     -- with split -->     |    |\n\
    \\ /                            |    |\n\
     C                             C1   C\n\
\n\
      -- with a global change -->  A     B\n\
                                    \\   /\n\
                                     \\ /\n\
                                      C\n\
\n\
Change only this instance:  Split the tree, making a new copy\n\
Change all copies:       	Make a global change \n\
Help:         			    This message."
