A lot of CSS/JS frameworks look for attributes on html elements that include a hyphen to do their magic (JQuery Mobile, Bootstrap, etc).
For example, in my JQuery Mobile app, I'd like to be able to say:
Unfortunately, this doesn't work because Freemarker doesn't allow hyphens in macro parameter names. I entered an enhancement request for this here: https://sourceforge.net/p/freemarker/bugs/395/
I'm not sure when or if that might be fixed, so perhaps a work around would be to allow explicit dynamic attributes through some kind of parameter convention.