onStart
The instruction(s) to be executed are placed within quotes. This event handler will execute the instruction(s) when the MARQUEE element has finished loading, and has started scrolling.

The following example will display text of your choosing in a message box when the MARQUEE element has finished loading, and has started scrolling:
onStart="msgWindow.document.write('-- Insert text message here --')"
This Event Handler is used with the following:

MARQUEE