This specification describes the functionality of the services provided by the Sensors and Indicators Unit (SIU) services under WOSA/XFS, by defining the service-specific commands that can be issued, using the WFSGetInfo, WFSAsyncGetInfo, WFSExecute and WFSAsyncExecute functions. This section describes the functions provided by a generic Sensors and Indicators Unit service. This service allows for the operation of the following categories of ports: - Door sensors, such as cabinet, safe or vandal shield doors. - Alarm sensors, such as tamper, seismic or heat sensors. - Generic sensors, such as proximity or ambient light sensors. - Key switch sensors, such as the ATM operator switch. - Lamp/sign indicators, such as fascia light or audio indicators. - Auxiliary indicators. - Enhanced Audio Controller, for use by the partially sighted. In self-service devices, the sensors and indicators unit is capable of dealing with external sensors, such as door switches, locks, alarms and proximity sensors, as well as external indicators, such as turning on lamps or heating.