xhtml_conform-7:If it encounters an entity reference (other than one of the predefined entities) ... the entity reference should be rendered as the characters (starting with the ampersand and ending with the semi-colon) that make up the entity reference
Tests for assertions xhtml_conform-7

This document does not validate against the DTD

xhtml_conform-7: &unknown; the previous unknown character entity must be printed as "&unknown;".