Sc_pdf Documentation

Hi all,
I have been wasting couple oh hours doing something very basic with PDFReport.
I need to position text in particular positions of the layout, with code (since I need to make a couple of lines and need to use code instead of layout).

I tried to use sc_pdf_set_xy and sc_pdf_print/sc_pdf_write, even following solution posted on the PDFReport Section, but I am not able to move the text.
Is there anywhere the documentation of the sc_pdf_XX functions ?

Code is:

sc_pdf_print_img($cell_BARCODE);
sc_pdf_print($cell_BigRiga);
sc_pdf_line(2,40,50,40);
sc_pdf_set_xy(2,45);
sc_pdf_print($cell_riga1);

Thanks, Federico