jQuery MetaData "data" attribute doesn't validate

Using the jquery metadata plugin, I have an element on my page that looks like this:

But, if I run this through the W3C Validator - I get an error saying "there is no attribute "data""

...have I misse开发者_JS百科d anything (I realise data isn't a valid attribute, but this seems to be a 'bug' in the metadata plugin is it? - not one that's going to get fixed anyway)

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For the metadata plugin, you put the data in the "class" string.

<div id='x' class='bigDiv purple spectacular {size: 200, weight: "19kg"}'>