dhcpd code options

In /etc/dhcpd.conf the line:

option option-066 "…";

gives error:

fatal in dhcpd: Configuration file errors encountered

dhcp-options(5) states:

Options ... may be defined by the name option-nnn where nnn is the
decimal number of the option code. ... For example:

option option-133 "my-option-133-text";
option option-129 1:54:c9:2b:47;

I've also tried `option-66`, `66`, putting it in different sections of the .conf file.

Am I missing something?

Thanks,
Ian