Launched in mid-2005, the New Series Adventures introduced a new format for Doctor Who fiction — paperback-sized hardcovers with smaller word count than the previous EDA and PDA lines. For a few months, the "NSA" line coexisted with the EDA and PDA lines, until they were retired at the end of 2005. With this series of books, BBC Books also established a release pattern it has continued ever since, releasing the books in batches of three, initially at least twice a year. The books are considered standalone and, thus, may be read in any order (at least among a particular set of three).