The author continues to substantiate the goal set by Arkady Sokolov to conceptualize the document entity. As the initial point, he took Sokolov’s definition of documentosophy as the segment of sociocultural space to build, transfer, preserve and user meaningful communication messages referred to as documents. Sokolov also refers to the sphere of sociocultural production where the documents emerge, circulate and are preserved, as the documentosphere. The author argues that the adequate definition of the document is possible in its dialectic object-subject perception according to the international definition: the document is an object or recorded information provided that in the given documentation process (rather than generally!) it can be considered (by a subject) as a discrete whole. This results in the need to specify restrictions and to formulate narrower definition of the document specifically for each individual documentation process. The fundamental provision of relativity, conformity and conventionality of the concept “document” is explained; the author criticizes the mediaology claiming to replace documentive concepts with medialogical structures. In fact, the subject of documentology coincides with that of mediaology. However, firstly, each science has its own term, and, secondly, these are just their approaches that differ, i. e. the ontological approach is applied in documentology, and the communicative one in mediaology. The mediaology has been diligently though unreasonably avoiding the concepts of “document” and “information”. Thirdly, as opposed to documentology, the mediaology has been still unable to propose any brand-new and valuable insight into the document phenomenon.