A method for computer assisted planning of a technical system with a first structure of multi-category objects is provided. Each multi-category object describes a technical component and includes a plurality of facets. Each facet is of a specific category and refers to information about the technical component. Categories of a multi-category object refer to different disciplines for designing a technical system. The disciplines include mechanical, electrical and automation engineering. Further, a second structure of a specific category is provided and has category-specific elements. Each category-specific element describes a technical component with respect to the corresponding specific category. Each facet of a specific category of a multi-category object describing a technical component in the first structure is related to a category-specific element of the specific category describing the technical component in the second structure. The first and second structures are changeable by a user during planning of the technical system.