Abstract: In a method for payment for services and/or goods, an apparatus with a data terminal device for reading and changing an amount value in a credit balance carrier and a security module provided with a first memory area and a second memory area is used, which is connected to the data terminal device via a communications channel. In a first transaction a usable amount is transferred from the credit balance carrier to the first memory area. During the purchase of the service and/or goods, a running cost amount for the service and/or goods, in a second transaction an unused amount is transferred from the first memory area to the credit balance carrier. In a third transaction the difference between the usable amount and the unused amount is transferred from the first memory area to the second memory area.

Abstract: A watertight housing, preferably for photographic or cinematographical dees, which has a cover sealed against the penetration of water, which cover can be opened for access to at least one part that is important for putting a device arranged in the housing into operation. Viewed from the outside--behind the cover seal a moisture detector is provided. At least one evaluating device with a warning or signal device is connected to the moisture detector.