Type of Cross Reference


Indicates the type of element to which a cross reference is pointing (e.g., to a figure, an author note, a bibliographic reference citation, etc.). These values may be used for type-specific processing or validation.


The <xref> element may be used to reference anything that has an Identifier id attribute. This single element takes the place of the many named types of references (such as figure references, table references, and footnote references) that are common in many journal DTDs. This attribute preserves the information from such DTDs concerning the type of element to which the cross-reference is pointing.

Attribute Values

In Element

<xref> X(cross) Reference
Value Meaning
aff Affiliation.
app Appendix.
aunote Author note.
bibr Bibliographic reference (to a <citation> or <ref"> element).
boxed-text Textbox or sidebar.
chem Chemical structure wrapper or chemical structure.
contrib Contributor.
corresp Corresponding author.
disp-formula Display formula.
fig Figure or figure group.
fn Footnote.
kwd Keyword.
list List.
plate Plate.
scheme Scheme.
sec Section.
statement Statement.
supplementary-material Supplementary material.
table Table.
table-fn A Footnote (<fn>) element that is found within a <table-wrap> element. Such footnotes should be displayed with the table rather than, for example, at the bottom of the page or screen.
other Something other than the named reference types.
Restriction: This attribute may be specified if the element is used.