Defines VHSIC Hardware Description Language (VHDL)accurately. Its primary audiences are the implementor of tools supporting the language and the advanced user of the language. Other users are encouraged to use commercially available books,tutorials,and classes to learn the language in some detail prior to reading this standard. These resources generally focus on how to use the language,rather than how a VHDL-compliant tool is required to behave. This publication has the status of a double logo IEEE/IEC standard