updates= parameter not being picked up

[Peter Scheie]

I'm launching the installer (anaconda) from an ISO and/or flash drive,
which are each using syslinux for the bootloader.  The syslinux.cfg file
loads the kernel and the initrd.img, and passes, for example, a ks=
parameter, all of which is working fine.  However, now I'm trying to add
a updates=http://server.com/path/to/updates.img parameter, and though I
see it when I Ctrl-F2 and cat /proc/cmdline, anaconda is not retrieving
the file from the http server.  The /tmp/anaconda log does, however,
show a request for updates.img being sent to the server where stage2.img
is downloaded from.  Any idea why it's not using the parameter I'm
passing at boot time?  Also, is it mandatory that the file name used for
updates be names updates.img?  Or could it be, say, updates-network.img?
Thanks.

Peter