The LocalSubmitFlag controls whether or not an OK/Cancel set of buttons appears on the pay page. If this option is set to “No” or “False”, then no buttons appear. It is assumed when this occurs that the parent (or eventual parent) page will contain an OK button that has a larger scope. Therefore, to cause the pay page to do its processing, we need a way for the parent to trigger that processing. This is accomplished by posting a message to the window containing the page pay. The message must begin with the text "JfsPayPageMessage_ProcessInput".
For example, if you have the pay page in an embedded iframe, you can use the “contentWindow” attribute of the iframe object and call “postMessage” like this [iframe].contentWindow.postMessage(“"JfsPayPageMessage_ProcessInput", “*”). Posting this message will fire off the page processing just like hitting the OK button on the pay page if it was there. The rest of the message processing as described above completes the interaction.