Downsides of using non-standard rel attributes on a link tag

Question

I was wondering: if I put in my page a link tag like so:

<link href="/path/to/template.mustache" rel="template" />

thus using an invalid rel attribute for a link tag element, could this come around and byte me in the ass later (like SEO problems, rendering issues in IE, etc) or it will create no more than just some invalid HTML ?

Also, considering that this is a link to a mustache template that will render a small part of the page, will it be more appropriate to use rel='subsection' ? I can't find more details about this rel attribute other than what is mentioned on w3schools.

Answer 1

No downsides if you do not use rel="nofollow" or some other specific rel, like "canonical" or "me". The reference for the rel attribute is in the XFN : http://gmpg.org/xfn/