Data definition in the programming language MARKIZ A way of data definition in an object-oriented programming language, which is designed mainly for constructing various language processors (including compilers, interpreters, and converters), is described. A special feature of the language is a nonconventional definition of the object type that can be used simultaneously as the description of a syntax class. Objects in a program are represented (denoted) as character strings that follow the grammatical rules given in the definitions of types. In the case of a compiler, for example, the object-program is represented by the source file itself. The availability of a constructor in the language makes it possible to generate objects while the program is running from components -- subobjects given either by variable values or in the form of representations.