The purpose of these papers is "to stimulate and inform debate about the 1962 Missal among Catholics ‘attached to the ancient Latin liturgical tradition’, and others interested in the liturgical renewal of the Church."
Paper number 20 deals with some of unique features of the Extraordinary Form calendar, which as we know contains a number of features not found in the Ordinary Form, notably the season of Septuagesima, the number and treatment of vigils, and the number of octaves.
The full paper can be read here.
All the papers thus far, numbers 1 to 20 can be downloaded here.