VHDL 2008 force/release feature absent from ncvhdl

Hi,

I try to use the VHDL 2008 to force a signal inside an instance.

In my VHDL-testbench file, inside a process, I have the following line:  

       <<SIGNAL u_dut.counter : SIGNED(5 DOWNTO 0)>> <= release;

I compile the file with:

    ncvhdl -V200X testbench.vhdl

The command returns something like:

       <<SIGNAL u_dut.counter : SIGNED(5 DOWNTO 0)>> <= release;

                                                                 |
ncvhdl_p: *E,IDENTU (testbench.vhdl,219|65): identifier (RELEASE) is not declared [10.3].

Please note that ncvhdl does not complain about the external name, meaning that the -V200X option is taken into account.

But why doesn't it recognize the VHDL 2008 'release' instruction ? Do I need to use a special package ?

Note: The 'force' instruction doesn't work either.