Used in conjuction with the "Facebook Application ID" setting on the Advanced tab of the Theme Manager.
Documentation about the comments box and the options it supports are located here: http://developers.facebook.com/docs/reference/plugins/comments
The xid for the Facebook comments tag is a unique identifier that it uses to store the comments for a given page or item. If you wanted the comments to be shared across a category you could provide the category ID. If you wanted them for a particular product you could use a product id or an item number. Note: The default value for a URL is not a valid xid value, if you plan to use a URL, it has to be encoded.
An example of a good xid value might be something like this (using nested merges):
We support all of the same options.
To put width=�325� in the fb:comments tag, then use
To use additional options, i.e. numposts=�2� width=�425� then use