The Institute of Oriental Manuscripts of the Russian Academy of Sciences (IOM RAS) has more than 100,000 manuscripts and xylographs in 60 Oriental languages. The Korean fund represents a small part of this collection, however the unique works of Korean culture stored in the IOM RAS are of interest to both researchers from the Republic of Korea and local Russian scientists. The article describes the difficulties of reading the text of the D-86 xylograph "Samseolgi jung" from the Manuscript Collection of the IOM RAS. The work highlights the main problems that a researcher may encounter when working with similar medieval sources of Korean culture written in the Korean alphabet (in Hangul). The author of the article analyzes some features of the Modern Korean language revealed in this xylograph and describes its differences from the language of the 15th century and from Contemporary Korean, using the study of texts written in Hangul in different centuries for comparison. Commented examples of the old orthography and different spelling variations of the same word are used to illustrate the peculiarities in the language of the source. This article also describes the features of writing the graphics of the text of the 19th century, which were not previously covered (in particular, the symbol of repetition of the previous syllable, which in its graphic form and function is similar to the repetition sign used in the Chinese language, and the abbreviation sign of the median predicative affix 고 /go/).