[Fontconfig] How can I match fonts with their lang?

[James Su]

Hi,
I want to match fonts with their lang tag, so I add following config
into fonts.conf:

<match target="font">
<test name="lang" compare="contains">
<string>zh</string>
</test>
...
</match>

But no effect. Could you please tell me how can I do that?

Regards
James Su