These are collections of documents needed to complete the process of Letter of Undertaking(LUT) for GST registrations. Getting this done helps in case you are working remotely from India and your clients are outside India. Though Service Exports are exempted under GST, without LUT you have to pay 18% tax and then claim the refund for each return.
Apart from these PDFs you would need ID Cards of the witness you have for the LUT, your PAN card and an additional ID proof. There is one more document missing from current set, GST-RFD-Form11, current format has tables in it, which I am yet to put together in LaTeX format.