The military charter is defined in the article as a major type of administration document in the Don Host Province (Rus. Oblast’ Voyska Donskogo) and is claimed to be an exceptional genre of administrative documentation of the 18th century. The study is conducted with reference to documents (dated between 1735 and 1755) from the Mikhailovsky Stanitsa Ataman Archive (State Archive of Volgograd Region). Applying a complex approach to linguistic phenomena analysis and taking into account the achievements of the modern text theory through the prism of documentation linguistics, the authors determine the following characteristics of any genre of a documentary text: functions, subjects of communication (addresser, addressee), specificity of the message delivered, composition structure, prevailing modality, time and space localization. The authors illustrate their multi-vector and heterogeneous interaction and coordination with the specific features and general text categories and properties of the text. The notion of genre that was first introduced in linguistics with reference to fiction is specified for documentation linguistics; conceptual information in official and administrative documents is considered as a cultural and historical background that helps to provide an accurate interpretation of factual information. The authors characterise the peculiarities of the aforementioned parameters in the speech structure of military charters that are expressed by different level means of language, emphasising the cases that allow for variability. The article demonstrates that though it is an isolated textual phenomenon, the military charter reflects the peculiarities of records management typical of a certain area of Russia. Keeping some old instructive traditions, the text, however, demonstrates some features of the new office style of the 18th century.