To access a VHDL package:
1.Use a library clause to include the library in which the package is compiled. For example:
2.Designate the package, or a specific definition contained in the package, with a use clause. For example: use library_name.package_name.all.
3.Insert these lines immediately before the entity or architecture in which you use the package definitions.
Because the work library is the default library, you can omit the library clause if the designated package has been compiled into this library.