The d4p_simpleBiblioset element is the element for parts of a bibliographic entry, such parts may be author name, title, and publication information. It is an inline element. You set each part via the @outputclass attribute, so your processing would be configured to do something on these elements according to their @outputclass attribute.
This element specializes from the ph element. To use, you may use this element with an @outputclass to identify the type (e.g., outputclass="author") or you may specialize this element so that the name reflects the part of the entry it is for (e.g., d4p_simpleBiblioAuthor, d4p_simpleBiblioTitle).
+ topic/ph d4p-bibbase-d/d4p_bibliosetBase d4p-simplebib-d/d4p_simpleBiblioset