Elements that may be included along with data characters inside the content model for the <preformat> element, in which whitespace, such as tabs, line feeds, and spaces, will be preserved
<!ENTITY % preformat-elements "| %access.class; | %address-link.class; | %display-back-matter.class; | %emphasis.class; | %subsup.class;" >
articleauthcustom-models.ent