Element class created to hold the <element-citation> and <mixed-citation> elements (which reference an external document, as used within, for example, the text of a paragraph) and the citation alternatives element <citation-alternatives> (which contains a single citation in multiple forms, for example, in two languages).
<!ENTITY % citation.class "citation-alternatives | element-citation | mixed-citation | nlm-citation" >
JATS-journalpubcustom-classes1.ent and JATS-journalpub-oasis-custom-classes1.ent