Syntax is CASE SENSITIVE .
<%ipi%>onload <- the script will be executed every time the page is loaded
<%ipi%>INIT <- the script will be executed only when the page is first loaded ( not reloaded )
<%ipi%>[your button name, case sensitive] - loaded when you press a certain button on your form
E.g. When pressed Submit button
<%ipi%>Submit
begin
if isparam('Submit') then writeln('You pressed the Submit button !');
end.
</%ipi%>