EP 1 499 943 B1 REFERENCES CITED IN THE DESCRIPTION Patent documents cited in the description • US 5396635 A  [0007] This list of references cited bytheapplicant is forthe reader’s convenience only.Itdoes notform part of the European patent document. Even though great care has been taken in compiling the references, errorsor omissions cannot be excluded and the EPOdisclaims all liability in this regard. 18