Logic library: can't select CCL clocksource::osc1k on AVR128DB48 (Curiosity Nano)

[SimonMerrett]

I understand that I should be able to select osc1k as my CCL clock source for the DB series but this macro seems to be stopping me

  // Use clocksource:: when working with logic clock source
  namespace clocksource {
    enum clocksource_t : uint8_t {
      clk_per      = 0x00,
      in2          = 0x01,
      #ifdef CCL_CLKSEL_gm
      oschf        = 0x04,
      osc32k       = 0x05,
      osc1k        = 0x06,
      #endif
    };
  };

Code otherwise compiles, flashes and runs fine on the Curiosity Nano if I use e.g. clk_per. What am I missing? CCL_CLKSEL_gm doesn't appear in ioavr128db48.h but CCL_CLKSRC_gm does - is that what we are after?