UNI 8290 is the Italian standard providing an ordered classification and terminology for the technological system of a building: it breaks the building down into a hierarchical tree of parts, giving each a shared name and code. It is the reference framework used — in state exams and in practice — to organise the "percentage breakdown of work categories": every item of work maps to a cell of the scheme. A voluntary technical standard published by UNI: its logic is described here, its text is not reproduced.
Description, classification and measurement of the parts of a building; terminological basis for specifications, bills of quantities and the work-incidence table required in the professional exam.
It organises the technological system into nested hierarchical levels: at the top the CLASSES OF TECHNOLOGICAL UNITS (the major functions of a building — structure, external closure, internal/external partition, services, internal/external equipment); below, the TECHNOLOGICAL UNITS (e.g. foundation structure, vertical closure, upper closure); finally the CLASSES OF TECHNICAL ELEMENTS (the concrete components). Each level carries a code, so any work item maps uniquely onto the tree. It is a taxonomy, not a set of performance requirements: it fixes no values, only the ordered way to NAME and GROUP the parts — which is exactly what makes it the backbone of measurements and incidence tables.
Where this rule shows up in past architect qualification exams — study the rule, not just the theme.
Because the tests often ask for the "percentage breakdown of work categories": UNI 8290 provides the categories (classes of technological units and technical elements) into which the project's works are split and weighted.