establishing, on a message receiving device, a receiver message model, the receiver message model specifying a message format for interpreting application messages, the receiver message model comprising one or more receiver field specifications, each receiver field specification specifying a message field for storing data in an application message, each receiver field specification comprising receiver field characteristics;

calculating, by the message receiving device, a receiver version number for the receiver message model in dependence upon the receiver field characteristics of one or more of the receiver field specifications of the receiver message model;

receiving, by the message receiving device from the message sending device, the application message and the sender version number for the sender message model;

comparing, by the message receiving device, the receiver version number with the sender version number; and

administering, by the message receiving device, the application message in dependence upon the comparison.