A possible reason for this is that the use of xlink:href, the attribute
used to render the text glyphs created by symbol elements in
https://wiki.contextgarden.net/images/5/54/layout.svg, has been deprecated
since SVG 2.0, as you can see in
https://developer.mozilla.org/en-US/docs/Web/SVG/Attribute/xlink:href

Instead, as the article recommends, just href should be used instead, and
the xlink:href attribute can be preserved as a fallback for (very) old
browsers.


-- 
Andrés Conrado Montoya
Andi Kú
andresconrado@gmail.com
http://sesentaycuatro.com
http://messier87.com
http://chiquitico.org
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Los fines no justifican los medios, porque la medida verdadera de nuestro
carácter está dada por los medios que estamos dispuestos a utilizar, no por
los fines que proclamamos.
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“You develop an instant global consciousness, a people orientation, an
intense dissatisfaction with the state of the world, and a compulsion to do
something about it. From out there on the moon, international politics look
so petty. You want to grab a politician by the scruff of the neck and drag
him a quarter of a million miles out and say, ‘Look at that, you son of a
bitch.’” — Apollo 14 astronaut Edgar Mitchell