We expect medieval glosses carried by a grammatical text to treat of grammar. This is certainly the case if one considers grammar in the sense of ‘all knowledge relating to texts’. In this respect, the old libraries show that the Libri grammaticorum also included non-grammatical texts of authors studied in the "school curriculum". Thus, most of the manuscripts that transmit these ‘school texts’ are abundantly provided with glosses, some of which provide grammatical explanations, while grammars itself have provided with glosses which have no immediate connection with this discipline. Within this extended framework, the metalinguistic activity of the masters conforms to a grammatical and philological hermeneutic process. The whole text goes through a detailed review: correctness and reliability of the text, lexical elucidations and their semantic complement, the division of signifying units and their constructions, all this information gave occasion to annotations. Glosses along with other kind of annotations - among those that may have influenced the reading and understanding of the text - thus testify to a true praxis. Moreover, grammarians have evolved in a surprisingly diverse linguistic context. During the reign of Charlemagne and during the following decades, people enjoyed great freedom of movement, as evidenced by the books accompanying them. The Carolingian schools were the privileged place for a mix of intense culture, where Italians, Spanishs, Irish, Anglo-Saxons and Franks rub shoulders and communicate thanks to Latin, the object of their attentions. These grammarians of all origins glossed the school texts according to a methodology that seems more or less consistently applied: the problem that will be explored here is to determine whether the mother tongue of the glossators influenced their grammatical practices. And if so, to what extent these practices originating from different (linguistic) backgrounds have mutually influenced each other. The article by Korhammer (Mittelalterliche Konstruktionshilfen und Altenglische Wortstellung, 1980) and the work of other researchers have proposed elements of response in favor of a school koinè. However, this conclusion is based on a too narrow documentary basis (only signs of syntactic construction) so that it can be extended to our questioning. After having distinguished different types of grammatical glosses, and in order to propose research tracks from a comparative perspective, this contribution will confront the grammatical practices (ninth century) from two linguistically distinct circles —Franks and Irish— that have worked in parallel on Priscian’s grammar.