An approach to organizing information interaction in a multilevel system of digital twins is considered. The unit of inter-level information exchange is a software structure of a special type — a package, built on the principle of organizing messages in HTTP(s)-protocols. Directly, the metadata of the data source is placed in the header of the package and allows identification / authentication of the corresponding resources as data arrives. The registered / calculated data of the digital twin or its physical prototype is placed in the body of the packet. One of the significant problems of such data organization is the format of the metadata block used in the packet header, which should be compact and accessible for analysis by data processing software. As a part of the research described in the article, an approach to encoding a header with metadata is proposed based on a combination of DTDL formats, intended for the semantic description of industrial digital twins, and JWT, which provides a procedure for maintaining a communication session between a client and a server in a web-oriented application architecture. The metadata is directly specified in the DTDL format and their placement in the package header is a software “fold” of data in the JWT token format replacing the cumbersome JSON description of the data source with lightweight text code. Studies carried out on the example of a multilevel system of digital twins of magnetic observatories and variation stations have shown the feasibility of the proposed solution in the context of reducing the physical volume of a data packet (header with metadata) formed during data transmission in comparison with the well-known approach based on a text or DTDL— description of metadata.