What is Javascript opener?

Hi, this little problem has got me in a confused state... it's partly BSP, partly Javascript - but the Javascript comes in a BSP View, so I feel it's fair to ask the question.

I have some ABAP code that calls a view (it's CL_CRM_BSP_F4_HELP method CALL_EVENT_TABLE in CRM 4.0, and the view is f4_values.bsp). The View appears as a popup window, and contains snippets of Javascript such as this:

function SubmitEvent(Event,ButtonGroupId,EventIndex)

{

opener.SubmitEvent.submit(Event,ButtonGroupId,EventIndex);

top.close();

}

My question is, what exactly is the "opener" object in this case? Normally another piece of Javascript in window A does something like "window.open" to open window B and that makes window A the "opener" of window B. But in this case, how can I find the "opener?" I would guess that the window.open command is created dynamically, so it is next to impossible to search for it.