We have now reached the Fifth Sunday after Pentecost in the traditional calendar, and, as I had a query about which calendar oblates should follow this week, I thought I'd try and set out the key issues here.
The Ordo notes I provide on this blog are based on the rubrics and calendar for the 1962-63 Benedictine Breviary, approved for use by all Benedictine monasteries and oblates attached to them. The calendar follows the broad pattern of Sundays and feasts in the Roman EF calendar, but differs in which saints feasts are celebrated and at what level in many cases.
The calendar applies to both the Mass and the Office, as the two are meant to reinforce each other. Individual monasteries will of course add their own particular feasts (dedication of the Monastery, patronal feasts and so forth), and each country, region and diocese will also have some particular feasts that should be celebrated in the Office.
It should be noted however that many monasteries do not actually follow this 'universal' Benedictine calendar.
In the case of monasteries using the Novus Ordo Mass, they could use updated universal calendar approved in 1977, or a calendar particular to their congregation. Ordos for the English Congregation, for example are available online.
In the case of monasteries following the Extraordinary Form, some monasteries follow the calendar for their particular Congregation, while others have adapted a calendar closer to the Roman EF calendar. A good example of this is Le Barroux, which also publishes an Ordo online.
In principle, Oblates are free to follow either the universal calendar, or the calendar followed by their particular monastery (adapted to add feasts particular to their diocese/region etc), assuming they can obtain a copy of it.
Where you go to a daily EF Mass other than in your monastery however, you will find that the Office and Mass do not always align (though the differences are generally minor). Accordingly, another possibility is to follow the Roman EF calendar for your Office as well, making use of the 'Commons of Saints' as appropriate.
In principle it is also possible to adapt the traditional structure of the Benedictine Office to the Novus Ordo calendar, however the Monastic Diurnal put out by the Farnborough monks does not provide you with the texts to do that (since the Lauds and Vespers antiphons, for example, are keyed to the EF Gospels, not the OF ones). So far as I am aware, the only approved books available for this purpose are in Latin only, in the form of the new Antiphonale Monasticum available from Solesmes. There is, however, an unofficial translation which you can find here.
This week in the 1962 Benedictine calendar
Sun 23 June Fifth Sunday after Pentecost, Class II
Mon 24 June Nativity of St John the Baptist, Class I
Tues 25 June Class IV
Wed 26 June Class IV; SS John and Paul, memorial
Thurs 27 June Class IV
Fri 28 June Vigil of SS Peter and Paul, Class II
Sat 29 June SS Peter and Paul, Apostles, Class I