vhdl-project-file-name

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

("\\1.prj")

Documentation:
List of file names/paths for importing/exporting project setups.
"\1" is replaced by the project name (SPC is replaced by `_'), "\2" is
replaced by the user name (allows you to have user-specific project setups).
The first entry is used as file name to import/export individual project
setups. All entries are used to automatically import project setups at
startup (see option `vhdl-project-auto-load'). Projects loaded from the
first entry are automatically made current. Hint: specify local project
setups in first entry, global setups in following entries; loading a local
project setup will make it current, while loading the global setups
is done without changing the current project.
Names can also have an absolute path (i.e. project setups can be stored
in global directories).

You can customize this variable.