TinyMCE configuration in Plone 5

Is it possible in TinyMCE to add 'data-stuff', maybe with the JSON config .

I am for example thinking of adding a pop-up style , turning
a href="someimage>
into
a class="pat-plone-modal" href="some image" data-pat-plone-modal="image: true >

I would use a normal style class and diazo.

It would be nice if it could be done without diazo, but if that is not possible, how do you add 'data-pat-etc" with a diazo rule ?

Why avoid diazo? It’s what its built for.

http://docs.diazo.org/en/latest/basic.html#merge

Means “data-pat-etc” has to be on something in your theme.
There is probably a XSL way of doing it as well.