I am using the TinyMCE (extended) that ships with Joomla.
When I use the link button to link an image to another page on the site it asks me to select an option for the 'rel' attribute within the href.
I am a bit confused about this - what value should I put for an internal link? I looked here http://www.w3schools.com/tags/att_a_rel.asp but it didn't really help. The select defaults to 'alternate' - which isn't really right.
If I use the 'article' button, my image is deleted and replaced with the title of the article.
What should I put?
(Assuming HTML5.)
There is no registered link type for "internal links". There are various link types that might be appropriate for some internal links, but not generally for all internal links. (And you are right that alternate is not appropriate.)
The registered external link type can be used for external links, so one might assume that every link without the external link type is an internal link.