Hi This is shankar
1. for load all sub file the page up and page down is handle by the system it self so
when you enter page down at last you have to identify the system defined symbol as well as page up.
2.for Expandable subfile page up is handled by the system if you enter page up at last you have to identify the system defined symbol that is called expandable sub file.
3.for single page subfile page up and page down is handled by the user so when you page or page down at top /bottam you have to identify the this ÿou have already reached the top/you have already reached the bottam this is called single page subfile