The DD tells the system what function blocks are present in a device type, what parameters are available, the data types of those parameters and the default values and permitted ranges of these parameters. This data is used by the system to understand a device even before the device is present in the system.

EDDL is based on DD technology. It represents a significant extension to the DD language, including:

• Additional graphic support (images, charts trends and graphs)
• Extended windowing support (windows, tabs, dialogs, parameter groups)
• Better computation capabilities (full math library support)
• File and data store and access (for history and trend access).

Using the DD enhancements in EDDL, a vendor can now develop support for advanced applications such as valve signature and other diagnostics that will work on any system supporting the enhancements. EDDL files are developed using the same tools and practices used by the DD technology, making support for them easier.

Related Feature - EDDL & FDT, Competing or Complementary?
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