The present invention relates to the field of perfumery, and more precisely to a compound of formula wherein R1 represents an C2 to C4 unsaturated hydrocarbon radical. In the method, digit keys are entered from a user, the call type and digit number requirement for a telephone number that the input digit keys represent are determined upon absence of input of a SEND key, and the telephone number is dialled if the input digit keys are complete, or after a predetermined standby time if the input digit keys are incomplete. The implants may be placed in an eye to treat or reduce a at least one symptom of an ocular condition, such as glaucoma. As a result, any advertising indicia or product information can be viewed by an observer, but the individual identification codes are obscured.