Elements that can be mixed with the data characters inside the various title elements, for example, inside <title>, <subtitle>, <trans-title>, etc.
Design Note: All inline mixes begin with an OR bar; since %simple-phrase; is an inline mix, the OR bar is already there and need not be added to %title-elements;.
<!ENTITY % title-elements
"%simple-phrase; | %break.class; |
%citation.class;" >bookcustom-models.ent