Abstract: A data handling system for multi-user transactions has a central data processing device incorporating a data store structured in accordance with a predetermined progressive transaction involving cooperation between users, and a plurality of data access interfaces for the device for the respective users with defined access privileges. At least some interfaces are read/write interfaces whereby data can be read from and written to the store in relation to predetermined stages of the transaction in accordance with the respective privileges.

Abstract: Infra-red light from an emitter is directed through a glass slide to an area on which a solid substance is located. Light reflected from the undersurface of the solid substance is received by a receiver. The substance is heated by a strip heater. When the substance changes state, the amount of reflected light arriving at the receiver varies, and information coming from an electronic thermometer records the temperature at which the change of state has occurred.