Syslinux - Nov 2003 - append or concat for dhcp-parameter-request-list

I'm confused...

A few months back I was playing with sending information to pxelinux by forcing
the dhcp server to send certain options.  I couldn't get the syntax:

append dhcp-parameter-request-list 208,209,210,211;

to work, but I was able to get

option dhcp-parameter-request-list = concat(option
dhcp-parameter-request-list,d0,d1,d2,d3);

to work.  This was with 3.0.1pl9.

Now with v3.0pl2 (the latest ebuild available for gentoo) and v3.0pl1 (on Red
Hat 9), the append syntax works and the concat syntax does not.

Which is the correct way to do this?

Thanks,

--Andy