The Lay Folk's Mass Book

I have always rather enjoyed the titles found within the Early English Text Society series, and was particularly interested to recently come across this particular title, which can be viewed in its entirety online, The Lay Folks Mass Book or, The Manner of Hearing Mass with Rubrics and Devotions for the People in Four Texts and Offices in English according to the Use of York taken from manuscripts of the 10th-15th centuries.