Unprinted papers are laid before each House but are not ordered to be printed as a House of Commons or Lords Paper. They include a large number of draft statutory instruments, reports of nationalised industries and some accounts. Many of these papers are actually published by The Stationery Office or the organisations concerned. Unprinted papers are public documents and can be consulted by the public in the Parliamentary Archives without restriction. There are on average 2,000 per year.
Further information on this subject can be found from the following link.
Parliamentary Archives