In HTML, you use boolean attributes with or without values as you like.
A boolean, for W3C, like autofocus can be written like that autofocus or autofocus="autofocus" or also autofocus="".
If you don’t want autofocus just don’t write it.
I think you are confused because XHTML requires values for all attributes: attributes="values".
Here is some information about boolean attribute use in HTML:
http://www.whatwg.org/specs/web-apps/current-work/multipage/common-microsyntaxes.html#boolean-attribute