The Book Switch Theory

[Koen G]

Relying on paleography to assign a manuscript to a time and place (however narrow or broad) is standard practice. You'd be surprised how often the date range provided in library catalogs is based on stylistic analysis of the handwriting alone. The most recent assessment by a professional paleographer (LFD) confirms that the marginalia were written during the (first half of the) 15th century. This is crucial and reliable information.