This means that data can be set in an embedded form e.g

 <af-entity data='{name_a : options.name_a,  name_b : options.name_b, is_name_b_nickname: options.is_name_b_nickname, is_name_b_inferior: options.is_name_b_inferior}' .... />

In this case the options.name_as comes from the directive that instantiates this afform