How to save PDF file with predefined name?

Hi,

I am new in LiveCycle Designer. I have a requirement to save a PDF file with predefined file name. When user clicks a "Save as PDF" button, the fillable form is saved with the name from the form fields (e.g. FormID_UserID_Timesstamp...)

I added a button (btnSavePDF) to the form (Control Type=Regular). Then I added an action with the Condition:"When button is clicked" and the Result: "Save the form". I got the JavaScripts it genreated:

CoverPageForm.FormPage.btnSavePDF::click - (JavaScript, client)

app.execMenuItem("SaveAs");

When I tested it in Adobe Acorbat XI, I have option to save it as .pdf or other file formats. My questions is how can I save it with the predefined file name as a .pdf file, instead user has option to change the file name or change the file format? Can app.execMemuItem() method take other parameters?

Thanks

Sam