The flattr directive is supplied by the flattr plugin.
This directive allows easily inserting Flattr buttons onto wiki pages.
Flattr supports both static buttons and javascript buttons. This directive only creates dynamic javascript buttons. If you want to insert a static Flattr button, you can simply copy the html code for it from Flattr, instead. Note that this directive inserts javascript code into the page, that loads more javascript code from Flattr.com. So only use it if you feel comfortable with that.
The directive can be used to display a button for a thing you have already manually submitted to Flattr. In this mode, the only parameter you need to include is the exact url to the thing that was submitted to Flattr. (If the button is for the current page, you can leave that out.) For example, this is the Flattr button for ikiwiki. Feel free to add it to all your pages. ;)
[[!flattr url="http://ikiwiki.info/" button=compact]]
The directive can also be used to create a button that automatically submits a page to Flattr when a user clicks on it. In this mode you need to include parameters to specify your uid, and a title, category, tags, and description for the page. For example, this is a Flattr button for a blog post:
[[!flattr uid=25634 title="my new blog post" category=text
tags="blog,example" description="This is a post on my blog."]]
Here are all possible parameters you can pass to the Flattr directive.
button- Set to "compact" for a small button.url- The url to the thing to be Flattr'd. If omitted, defaults to the url of the current page.uid- Your numeric Flattr userid. Not needed if the flattr plugin has been configured with a globalflattr_userid.title- A short title for the thing, to show on its Flattr page.description- A description of the thing, to show on its Flattr page.category- One of: text, images, video, audio, software, rest.tags- A list of tags separated by a comma.language- A language code.hidden- Set to 1 to hide the button from listings on Flattr.com.