WordPress is based on the idea of an article being constructed of blocks of various kinds – paragraphs, lists, images etc. So a simple article would consist of a series of paragraph blocks.

Engole hooks into that idea in two ways: by adding new blocks such our citation and attribution blocks, and by modifying the way that the contents of WordPress blocks are displayed, with the use of cascading style sheets (CSS).

And this is how it’s done:

Wikimedia Commons