It is quite clear that the monastery was under the influence of the Hirsau reform. See article by Janka Szendrei in bibliography; the comparison with south German sources, such as the Zwiefalten antiphoner (Karlsruhe, Badische Landesbibliothek - Musikabteilung, Aug. LX), seems to confirm it.
*It is problematic that this antiphoner contains almost no rubrics.* For example, the distribution of antiphons for the weekdays is not clear. It is evident, however, from the size of the initials that the chants are organized, and are not merely unstructured lists of items. The initials suggest a distribution of items for individual days of the week even when there are no explicit rubrics. Since the Office of the St. George monastery is well documented – it is one of the most numerous manuscript collections in Czech libraries – concordances have been located in two breviaries from the same époque: (See online images of these breviaries in the Manuscriptorium digital library: http://www.manuscriptorium.com/apps/main/en/index.php)
1. The breviary of Kunegunda of Kolovraty, a nun who commanded the manuscript between 1365 and 1385, shortly before she became abbess of the St. George Monastery. Shelfmark: Prague, Národní knihovna (National Library), XIII E 14a.
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2. Shelfmark: Prague, Národní knihovna (National Library), XIII C 1a
Click (as of 2012): http://www.manuscriptorium.com/apps/main/en/index.php?request=show_recor...
Comparison with these two breviaries has enabled interpretation of the St. George monastery antiphoner in some ambiguous situations.
The differentiae of each mode have been numbered with a two-digit system: an upper-case letter indicating the final pitch of the differentia and a sequentially-ordered numeral.
Václav PLOCEK: Catalogus codicum notis musicis instructorum, qui in Bibliotheca publica rei publicae Bohemicae socialisticae in Bibliotheca universitatis Pragensis servantur I, Praha 1973.
Janka SZENDREI: Prager Quellen zum Hirsauer Choral, in: Cantus Planus, Sopron 1995, p. 555-571.