if atc("FOXTOOLS.FLL", set("LIBRARY")) =  0 
   local lcFoxToolsLibrary, llSuccess
   lcFoxToolsLibrary = addbs(sys( 5 )+sys( 2003 ))+"FOXTOOLS.FLL"	
   if !file(lcFoxToolsLibrary)
      return .f.
   endif
   try
      set library to (lcFoxToolsLibrary) additive
      llSuccess = .t.
   catch
   endtry
   if !llSuccess
     return .f.
   endif 

   ......
endif