vhdl-project

vhdl-project is a variable defined in `vhdl-mode.el'.
Its value is

nil

Documentation:
Specifies the default for the current project.
Select a project name from the ones defined in option `vhdl-project-alist'.
Is used to determine the project title and description to be inserted in file
headers and the source files/directories to be scanned in the hierarchy
browser. The current project can also be changed temporarily in the menu.

You can customize this variable.