It is the boards' settled case law that a "kit-of-parts" described the juxtaposition of separate but functionally interacting individual components.

In T 9/81 (OJ 1983, 372) the board held that combined preparations, the individual components of which represented known therapeutic agents, might be protected in a formulation corresponding to Art. 54(5) EPC 1973 (now Art. 54(4) EPC) even when claimed as a kit-of-parts, providing those components formed a functional unity (true combination through a purpose-directed application. Claim 1 referred to a combined preparation containing an oxazaphosphorin cytostatic agent and the sodium salt of 2-mercapto-ethane-sulphonic acid as therapeutic active ingredients. The first-mentioned component of the product was known, and the second was a known mucolytic agent. According to the documentary prior art available to the board, the two active ingredients had never been used together for a new joint effect and were unknown as a composition. The active ingredients which were administered preferably at the same time according to the invention did not therefore represent a mere aggregate of known agents, but a new combination with the surprising, valuable property that the severe side-effects to be expected when administering the cytostatic agents were absent as a result of the detoxifying effect of the sodium 2-mercapto-ethane-sulphonate.