The texts presented by the app are based on those prepared by the Divinum Officium Project, and in most cases, we follow the changes they make. Recent changes have given a different meaning to two of the choices in the app for rubrics, namely those currently (version 1.8) labeled “Pre-Trent Monastic” and “1960 rubrics with 2009 calendar.”
The Monastic option will be modeled on the 1963 Monastic breviary. Previously, it was a reconstruction of the pre-Trent office for the purpose of comparing it with other historical versions. This change will make it more useful for monks who pray the traditional Benedictine office today. It also means that there will be an actual printed edition to use as a model. Work on this is in progress.
The “1960 rubrics with 2009 calendar” was an experimental version prepared in the latter year: it used the Novus Ordo sanctoral cycle with the 1960 rubrics and temporal cycle. In 2011, Universae Ecclesiae indicated that an official solution would be forthcoming, and finally on 25 March 2020, CDF decree Cum sanctissima (dated 22 February 2020) was published. This option has therefore been changed to conform to Cum sanctissima. If you wish to take advantage of the provisions of the decree, and the saint you wish to celebrate is in the Novus Ordo calendar of the United States, then this option will allow you to celebrate the saint and make any necessary commemorations. Since the changes are recent, it seems prudent to beware of possible errors, in particular missing commemorations.
For more information on the rubrical versions available, see the details on the Divinum Officium Project website.