Key to the HART Protocol’s ability to “get data out of the field device” is a data file called a Device Description (DD). This describes the features and functions of a device, such as the form and content of menus and graphic displays to be presented in host computers or handheld devices. The DD is written in conformance with a Device Description Language in the protocol. The HART Communication Foundation manages a library of Manufacturer Device Descriptions, and provides regular updates to which any Foundation member can subscribe. DD’s are available for download at this website. The DD is not required for communication with HART-enabled devices. It is an optional enabling element of HART technology that most device and host suppliers support in order to offer HART Users the added value of multi-vendor interoperability