Set URL of "like" button embedded in Facebook comments plugin

How can I set the URL of the "like" button embedded in the Facebook comments plugin?

The XFBML <fb:like>开发者_Python百科 tag has an href attribute, but the <fb:comments> tag lacks an equivalent attribute.

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The url attribute seems to be deprecated. There are two new attributes returnurl and callbackurl but they have no effect on the LIKE url. Maybe it's a question of time, I don't know. I cretaed a new app, changed the og:url attribute but still no luck. It keeps on "liking" the same page.

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updated for new version of Facebook comments plugin:

The new Facebook comments plugin no longer uses the xid attribute. Instead, the href attribute is used to both identify the comments box and associate a URL with it.

Compare new <fb:comments> to legacy <fb:comments>

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original answer:

Figured it out while asking the question:

The <fb:comments> url attribute works like the <fb:like> href attribute.