Chapter 20. Attributes and Groups
VHDL provides comprehensive facilities for expressing the behavior and structure of a design. VHDL also provides the attribute mechanism for annotating a model with additional information. In this chapter, we review the predefined attributes and show how to define new attributes. We also look at the group mechanism, which allows us to describe additional relationships between various items in a model.
Throughout this book we have seen predefined attributes that are used to retrieve information about types, objects and other items within a model. In this section we summarize the previously introduced attributes and fully describe the remaining predefined attributes.
VHDL-87 provides two ...