"Warning from Netsurf"

I have just seen an error message of a sort I've never seen before:

Warning from Netsurf
(that's the title bar of the RiscOS panel)

WARNING !!! Your browser is too old and will not display the
page optimally !
(screechmarks are spaced exactly like that)

The only action button provided is "Continue"

This warning popped up when I tried to visit
www.cordless-phones.uk.com/cordless-phones/cordlessphones-answering-machine/bt-synergy-4500-dect

I inspected the HTML source of this page and can't see anything to
generate such a warning from the browser. It's repeatable.

So I'm curious:

1. By what process was this message generated?
2. Is it indeed Netsurf that generates the message? If so, it's
ironic that I'm using a very recent build, Netsurf #2124.
3. Why is the error message not recorded by Syslog?

The display of the page, by the way, seemed OK despite the warning.
(Anyway, it was good enough to tell me what I wanted to find out about
the cordless phone in question.)

Using Iyonix with OS 5.18.

--
Jim Nagel www.archivemag.co.uk
|| See you at the show? www.riscoslondonshow.co.uk Oct 25