examples 
   below.  The file is a normal GEOS VM File; you may use 
   <A HREF="../../Memory/VM/VM_7.htm">normal VM routines</A> 
   with it.</P>

<P>Because the Viewer library only supplies a reference to the 
   document file when that file is to be opened, your library 
   will probably need to cache a reference to the file for 
   future operations.  It's a good idea to keep the file open 
   while the user is working with the document, so that the 
   system's file-sharing protection will keep other p