1. A machine for designing the logical structure of a large computer program, the machine comprising (a) an input device (11) capable of entering into processing unit (12) of the machine a collection of informational words (10), numerically describing links between different portions of the computer program, said portions being called "logical parts", each link representing a transfer of control of data processing action from one logical part through its port, said port being called "exit", to the port of another logical part, said port being called "entrance"; each informational word containing at least seven numbers, of which three numbers-a logical part number, an exit number, a program line number of the exit-are attributes of the exit of one logical part, the other three of said seven numbers are attributes of the entrance of the linked logical part, said collection of informational words being called "parent collection"; (b) said processing unit (12) having an algorithm of memorizing the entered parent collection and performing a search of informational words by the attributes of a logical part; (c) an output device (15) providing a hard copy printout of informational words (16) arranged in a consecutive order of the numbers of logical parts.