The Face Object Field - Content
Style/content is an optional field used to create compound styles. The field holds a GUI draw dialect block that defines the layout of the compound style.
For example, an area style has:
content: [ field-area :text-edit :text-color scroller ]
Note that the content block within a style is also slightly different because get-words can be used to pass optional fields from the main face to the subfaces. Above the text-edit and text-color values are passed to the new field-area.