Systems in the home of older and disabled people, must be appropriate, and this means they are required to be accepted by the user (so they will be used), trustworthy (so they do not breakdown or fail), adaptable (so they can be added to in the future and reset as the person's needs change as well as being "fit for the purpose", by which we mean they do what they say on the packet, they do what the user expects them to do, when the user expects them to do it, in the manner the person expects them to do it.