Abstract
In order to standardize time-related reports in clinical chemistry, basic concepts like system, component and kind-of-quantity are recalled. Changes of a quantity, and of chemical and physical processes involved in these changes are refined. Starting from the general format recommended by IUPAC and IFCC, including system, component and kind-of-quantity, recommendations are formulated. Specifications, especially time-related information, may be added in parentheses after each part of the format. Interrelated specifications are given after the kind-of-quantity. This paper provides examples of various specifications which show that all these elements are necessary for reporting time-related data.