XML Tagging Guidelines  


NCBI BookShelf Tagging Guidelines


square Elements


Tools & Resources

Elements

These XML elements have specific style rules associated with them. This is not a complete list of XML elements included in the Book Interchange Tag Suite. For guidance using elements not listed here, consult the Tag Library.

<abstract>
Chapters or books may contain more than one abstract.
Capture only the abstract in this tag. Other metadata like copyright information, citation information, and keywords are not part of the abstract.
Sections within abstracts must have either a <title> or a <label>. If neither exists, do not use <sec>. Do not use @sec-type on <sec> within abstracts.
Use the <trans-abstract> element to tag abstracts in languages different from that of the primary chapter.
<aff>
Set any label or symbol in the <label> element. Do not create symbols or labels in the XML if they do not exist in the published document. Follow copy for all punctuation.
Tag all non-label content as simple text within the element. Do not tag individual address elements in the affiliation. The only exception is email addresses which should be identified in <email>.
See Author/Affiliation Relationship for information on how authors and affiliations are “linked”.
<aff-alternatives>
Used to capture one affiliation in multiple languages or for multiple purposes.
<aff-alternatives id="aff1">
  <aff xml:lang="ja-Jpan">国立言語学博物館</aff>
  <aff xml:lang="en">National Museum of Linguistics</aff>
</aff-alternatives>
		
<alternatives>
<alternatives> may only be contained in the following elements
When alternatives are specified in these elements, Bookshelf will choose the alternative for display based on the following priority (broken down by category).
Category:Included elements:Processing priority:
Display text: <disp-quote>

<boxed-text>
<textual-form>

<graphic>
Formulas and

chemical structures:
<chem-struct>

<chem-struct-wrap>

<disp-formula>

<inline-formula>
<mml:math>

<tex-math>

<graphic>
Signatures: <sig>

<sig-block>
<graphic>

<textual-form>
Supplementary

material
<inline-supplementary-material>

<supplementary-material>
<media>

<graphic>

<table>

<textual-form>
Appendix <app> <textual-form>

<media>
Array <array> <tbody> (inside <table>)

<preformat>

<textual-form>
Figures <fig> <media>

<graphic>
Glossary <glossary> <textual-form>

<graphic>
Table <table-wrap> <table>

<array>

<graphic>

<preformat>

<textual-form>
Table cells <td>, <th> <textual-form>

<media>

<graphic>

If none of these objects exist in the <alternatives> element, the document will fail to pass PMC style. Contact Bookshelf if your data cannot be captured using these combinations.
If a child element of <alternatives> specifies @specific-use "online-only" or "online", that attribute will override Bookshelf's default processing and that object will be displayed in Bookshelf's rendering.
Some elements must not contain a child of <alternatives> that is the same element as itself. The following are not allowed: array, chem-struct, inline-supplementary-material, supplementary-material
<author-notes>
Tag notes directly related to the author(s) in <author-note>. If the information can be captured by the attributes available on <contrib>, do not include it as an author note. Tag correspondence information (beyond a simple corresponding author yes/no; see Author Names) in <corresp>. Set all other author-related footnotes in <fn>. Appropriate @fn-type values include:
ValueMeaning
comdocument was communicated by
condocument was contributed by
COI-statementConflict of interest statements
current-affcurrent affiliation
deceasedPerson has died since the document was written
equalcontributed equally in the creation of the document
present-addresscontributor's current address
Jane Doe and Marcus Dorsey
Please address all correspondence to Jane Doe at author@affiliation.edu.
  			<contrib-group>
  			<contrib contrib-type="author">
  			<name><surname>Doe</surname>
  			<given-names>Jane</given-names></name>
  			</contrib>
  			<contrib contrib-type="author">
  			<name><surname>Doresy</surname>
  			<given-names>Marcus</given-names></name>
  			</contrib>
  			<contrib-group>
  			... 
  			<author-notes>
  			<fn id="FN1">
  			<p>Please address all correspondence to Dr. Jane Doe at 
  			<email>author@affiliation.edu</email>.</p>
  			</fn>
  			</author-notes>
  		
<award-id>
Tag only one award id per <award-id> element.
<back>
Typical content includes (but is not limited to) appendices (<app-group>), glossaries (<glossary>), reference-lists (<ref-list>), and chapter-level footnotes (<fn-group>).
Do not set <title> or <label> on <back>.
<body>
Carries all of the chapter body. It allows <p> and all paragraph-level objects and then repeating recursive sections (<sec>).
Use <sec> to enclose all subsections within the body or within a section. Do not just set the section titles in <bold> or some other formatting.
Back matter elements, such as <app-group>, <glossary> and <ref-list>, should be tagged in <back>, not at the end of <body>.
<caption>
Within the caption, tag the <title> separately from from the rest of the caption text. Do not include the object’s label in <caption>; use the <label> tag.
<citation-alternatives>
Used to capture one citation in multiple languages, formats, or for multiple purposes. If a <ref> contains multiple citations, do not use <citation-alternatives>; see <ref>.
<ref>
  <citation-alternatives>
    <element-citation publication-type="journal" publication-format="print">
      <name><surname>Petitti</surname><given-names>DB</given-names></name>
      <name><surname>Crooks</surname><given-names>VC</given-names></name>
      <name><surname>Buckwalter</surname><given-names>JG</given-names></name>
      <name><surname>Chiu</surname><given-names>V</given-names></name>
      <article-title>Blood pressure levels before dementia</article-title>
      <source>Arch Neurol</source><year>2005</year><month>Jan</month>
      <volume>62</volume><issue>1</issue><fpage>112</fpage>
      <lpage>116</lpage>
  </element-citation>
  <mixed-citation publication-type="journal" publication-format="print">
      <name><surname>Petitti</surname><given-names>DB</given-names></name>, 
      <name><surname>Crooks</surname><given-names>VC</given-names></name>,
      <name><surname>Buckwalter</surname><given-names>JG</given-names></name>,
      <name><surname>Chiu</surname><given-names>V</given-names></name>.
      <article-title>Blood pressure levels before dementia</article-title>.
      <source>Arch Neurol</source>. <year>2005</year> <month>Jan</month>;
      <volume>62</volume>(<issue>1</issue>):
      <fpage>112</fpage>-<lpage>116</lpage>.
    </mixed-citation>
  </citation-alternatives>
</ref>
		
<collab>
<collab-alternatives>
Used to capture one collaborative author in multiple languages or for multiple purposes. See also <name-alternatives>.
<collab-alternatives>
  <collab>脳卒中急性期患者データベース構築研究(JSSRS)グループ</collab> 
  <collab xml:lang="en">JSSRS Group</collab>
</collab-alternatives>
		
<contrib>
Tag only one contributor per <contrib>.
Only use the @corresp, @deceased, and @equal-contrib attributes when the book or book-part does not have notes conveying the same information.
Whenever possible, tag the contributor’s affiliation inside the <contrib> tag. See Author/Affiliation Relationship for examples.

attributes:
  • contrib-type—
    Value is usually "author" or "editor". Attribute is required unless <contrib> is a descendant of <collab>.
  • corresp—
    Set as "yes" if the author is listed as the corresponding author.
  • deceased—
    Set as "yes" if the author is indicated to have passed on.
  • equal-contrib—
    Set as "yes" on each author that is indicated to have "contributed equally to this work".
  • id—
    Do not use. Set contributor identifiers in <contrib-id>.
  • rid—Do not use.
<contrib-group>
Contains one or more <contrib>
When used inside <collab> to tag collaboration members, it must not contain descendant <collab> elements.
If affiliation information is presented for the entire contributor group, tag the <aff> element inside the <contrib-group>.
See Author/Affiliation Relationships for more information.
<contrib-id>
Identifier of a contibutor as assigned by the authority named in @contrib-id-type.
Do not use on collaborative contributors.
<contrib contrib-type="author">
  <contrib-id contrib-id-type="orcid">http://orcid.org/0000-0002-7361-560X</contrib-id>
  <name><surname>Randall</surname><given-names>LA</given-names></name>
</contrib>
			
<copyright-statement>
Contains the complete copyright statement as it appears in the source.
The contents will usually be the word "Copyright", a copyright symbol, the copyright year, and the name of the copyright holder. Tag the year of copyright in <copyright-year>, whether or not it appears as part of the <copyright-statement>.
Must be contained in <permissions>.
<copyright-year>
Contains only the 4-digit year of copyright.
Must be contained in <permissions>.
<corresp>
Set any label or symbol in the <label> element. Do not create symbols or labels in the XML if they do not exist in the published document. Follow copy for all punctuation.
Tag all non-label content as simple text within the element except for email addresses which should be tagged in <email>.
<day>
Must be an integer from 1-31.
<element-citation>
Do not include punctuation. Tag reference that require punctuation in the XML with <mixed-citation>. See the citation examples for examples using both <element-citation> and <mixed-citation>.
<ext-link>
Used to tag link information to objects outside of the book.
See additional rules for usage in <license> under Licensing Information.

attributes:
  • ext-link-type—Holds an identifier of the external resource.(#REQUIRED)
  • xlink:href—Holds an identifier of or locator to an object available through or at that resource.(#REQUIRED)
<fig>
Floating <fig> elements (location in content does not affect meaning) should be tagged at the first reference to the <fig>. Unreferenced floating <fig> elements should be tagged in <floats-group>. All floating <fig> elements should include @position="float". Anchored <fig> elements (location in content does affect meaning) must be tagged with @position="anchor".

attributes:
  • id—(#REQUIRED)
  • position—Use "anchor" for an inline-figure, including figures that are contained within another object (<fig>, <table>, <media>) Use "float" for all other figures.
<fig-group>
See Display Object Groups for information on when to use this element.
<floats-group>
Tag all unreferenced, floating objects (<fig>, <table-wrap>) in this element with @position="float".
<fn>
Tag footnotes specifically relating to contributors in <author-notes>.
Information concerning grants, contracts, sponsors, or other funding for the research should be captured in <funding-group>.
Tag table footnotes in <table-wrap-foot>.

attributes:
  • id—(#REQUIRED)
  • symbol—Do not use. Capture information in <label>.
<funding-group>
Tag only information about the reported research funding. Do not tag copyright or license information in <funding-group>.
<funding-statement>
Tag the complete funding statement in this element, regardless of whether or not other elements within the <funding-group> duplicate the information. Bookshelf displays the content of <funding-statement> and does not use other funding elements to build display content.
<graphic>
Describes an external file containing a still image. Usually contained within <fig>.
Use <inline-graphic> for images appearing in the flow of text.

attributes:
  • xlink:href—The name of the file.(#REQUIRED)
<inline-supplementary-material>
Describes supplementary material that must be displayed in the textual flow of a chapter.
Include the full filename, including file extension, in the @xlink:href value on <inline-supplementary-material>.
<label>
Contains label information only (Table 1, Figure 1). Does not include <caption> data, such as <title>.
Do not include emphasis that encompasses the entire contents.
<license>
Contains license information for the book or chapter. Do not tag copyright information in the <license> tag.
Must be contained in <permissions>.
Whenever possible, include a URI to the license description using @xlink:href.
<license license-type="open-access" 
  xlink:href="http://creativecommons.org/licenses/by/2.5/">
  <license-p>This is an open-access article distributed under the terms of the 
  Creative Commons Attribution License, which permits unrestricted use, 
  distribution, and reproduction in any medium, provided the original 
  work is properly cited.</license-p>
</license>
	
<license license-type="open-access">
   <license-p>This work is licensed under a Creative Commons Attribution 
      3.0 Unported License. To view a copy of this license, visit 
      <ext-link ext-link-type="uri"  xlink:href="http://creativecommons.org/licenses/by/3.0/">
      http://creativecommons.org/licenses/by/3.0/</ext-link>
   </license-p>
</license>
  		
<list>
<list> may or may not have a title. It must have one <list-item> for each point in the list.

attributes:
  • list-type—Allowed values: "order", "bullet", "alpha-lower", "alpha-upper", "roman-lower", "roman-upper", "simple".(#REQUIRED)
  • prefix-word—This is for a word that should prefix the generated label in the list, eg. "Step".
<list-item>
Contains exacty one item per tag. Each item may contain multiple <p> elements.
Do not use <label> unless @list-type="simple".
<lpage>
The numeric last page of the book or chapter
<media>
Describes an external file containing a media object.

attributes:
  • xlink:href—The name of the file, including file extension(#REQUIRED)
  • mimetype—Mimetype of the file, such as video or application
  • mime-subtype—Mime-subtype of the file, such as pdf, xls, or mp4
<mixed-citation>
Maintain all punctuation from the original copy. Tag a minimum of the following tags if they are part of the original citation: <name> of the author, editor, etc.; <source>; <year>; pagination; DOI.
See the citation examples for examples using both <element-citation> and <mixed-citation>.
<mml:math>
<mml:math> is the root element for MathML.
Breaking long formulas
Do not set long formulas in tables <mml:mtable> just to get them to break. Capture potential or desired breaks with <mml:mspace> with @linebreak="goodbreak". If the formula was broken in a print version, enter a <mml:mspace> with @linebreak="goodbreak" at that point, and the break will be used if necessary during rendering.
Subscripts and Superscripts with Fences:
Elements <mml:msub>, <mml:msup>, and <mml:msubsup> must enclose the entire contents of the expression they affect, not just the closing fence. Fences include: ] } ) x03009; x0232A; x027E9; .
(x + y)2
Correct Tagging (where the 2 is superscript 
to the entire expression):
<mml:math>
   <mml:msup>
      <mml:mrow>
         <mml:mo>(</mml:mo>
         <mml:mi>x</mml:mi>
         <mml:mo>+</mml:mo>
         <mml:mi>y</mml:mi>
         <mml:mo>)</mml:mo>
      </mml:mrow>
      <mml:mn>2</mml:mn>
   </mml:msup>
</mml:math>
		
Incorrect Tagging:
<mml:math>
   <mml:mo>(</mml:mo>
   <mml:mi>x</mml:mi>
   <mml:mo>+</mml:mo>
   <mml:mi>y</mml:mi>
   <mml:msup>
      <mml:mo>)</mml:mo>
      <mml:mn>2</mml:mn>
   </mml:msup>
</mml:math>
		
Child Element Restrictions:
These elements require exactly 2 child elements. If either of the sub-expressions is complex, wrap it in an <mml:mrow>.

  • <mml:mfrac> — the first child is the numerator, the second the denominator.
  • <mml:mroot> — the first child is the base, the second is the index.
  • <mml:msub> — the first child is the base, the second is the subscript expression.
  • <mml:msup> — the first child is the base, the second is the superscript expression.
  • <mml:munder> — the first child is the base, the second is the underscript.
  • <mml:mover> — the first child is the base, the second is the overscript.
These elements require exactly 3 child elements. If any of the sub-expressions is complex, wrap it in an <mml:mrow>.

  • <mml:munderover> — the first child is the base, the second is the underscript, the third is the overscript.
  • <mml:msubsup> — the first child is the base, the second is the subscript expression, the third is the superscript expression. The subscript and superscript will be stacked.
Allowed only as children of <mml:mmultiscripts>

  • <mml:mprescripts>
  • <mml:none>
Allowed only as children of <mml:semantics>

  • <mml:annotation>
  • <mml:annotation-xml>
Allowed only as a child of <mml:math>

  • <mml:semantics>
MathML Attribute Requirements:
The MathML 1.01 style attributes listed below have been deprecated in MathML 2.0, and should not be used. http://www.w3.org/TR/2003/REC-MathML2-20031021/chapter3.html#presm.deprecatt
Namevaluesdefault
fontsizenumber v-unitinherited
fontweightnormal | boldinherited
fontstylenormal | italicnormal (except on
<mi>
)
fontfamilystring | css-fontfamilyinherited
color#rgb | #rrggbb | html-color-nameinherited
These depricated attributes should be replaced with the appropriate new mathematics style attributes, described here: http://www.w3.org/TR/2003/REC-MathML2-20031021/chapter3.html#presm.commatt
@mathvariant:
Only the following values are allowed for this attribute: ( normal | bold | italic | bold-italic | double-struck | bold-fraktur | script | bold-script | fraktur | sans-serif | bold-sans-serif | sans-serif-italic | sans-serif-bold-italic | monospace )
@numalign, @denomalign, @columnalign:
Only the following values are allowed for these attributes: ( left | center | right )
@rowalign:
Only the following values are allowed for this attribute: ( top | bottom | center | baseline | axis )
@groupalign:
Only the following values are allowed for this attribute: ( left | right | center | decimalpoint )
@equalrows, @equalcolumns, @bevelled:
Only the following values are allowed for these attributes: ( true | false )
@display:
Only the following values are allowed for this attribute: ( inline | block )

attributes:
  • id—(#REQUIRED)
<month>
Must be an integer from 1-12.
Tag any month range (January-March) as a <season>.
<name-alternatives>
Use when tagging a single name in multiple languages or forms.
<contrib contrib-type="author">
  <name-alternatives>
    <name>
      <surname>Canut Jordana</surname>
      <given-names>M Isabel</given-names>
    </name>
    <name content-type="index">
      <surname>Canut</surname>
      <given-names>MI</given-names>
    </name>
  </name-alternatives>
</contrib>
		
<name-alternatives>
  <name name-style="eastern" xml:lang="ja-Jpan">
    <surname>中西</surname>
    <given-names>秀彦</given-names>
  </name>
  <name name-style="western" xml:lang="en">
    <surname>Nakanishi</surname>
    <given-names>Hidehiko</given-names>
  </name>
  <name name-style="eastern" xml:lang="ja-Kana">
    <surname>ナカニシ</surname>
    <given-names>ヒデヒコ</given-names>
  </name>
</name-alternatives>
		
<notes>
Used for book- or chapter-level notes. These often appear at the beginning or end of the document.
Tag notes relating to the author(s) in <author-notes>.

attributes:
  • notes-type—Set as "disclaimer" for article disclaimers. Set as "note-in-proof" for notes in proof.
<on-behalf-of>
Used when a contributor is participating as a representative of an organization. Do not confuse with <collab>.
Rodrigo Teresa, Joan A Caylà, and Martí Casals for the Working Group on Completion of Tuberculosis Treatment in Spain
<contrib-group>
  <contrib contrib-type="author" corresp="yes" id="A1">
    <name>
      <surname>Rodrigo</surname>
      <given-names>Teresa</given-names>
    </name>
  </contrib>
  <contrib contrib-type="author" id="A2">
    <name>
      <surname>Caylà</surname>
      <given-names>Joan A</given-names>
    </name>
  </contrib>
  <contrib contrib-type="author" id="A3">
    <name>
      <surname>Casals</surname>
      <given-names>Martí</given-names>
    </name>
  </contrib>
  <on-behalf-of>Working Group on Completion of Tuberculosis Treatment in Spain</on-behalf-of>
</contrib-group>
<open-access>
Used to hold text describing funding used to pay any open access fees associated with the documents's publication. Do not include the license text (see <license>).
<p>
Paragraph. Contains text of book.
<pub-history>
Contains one or more <date> elements describing the document's processing history.
Common history dates include created, received, accepted, updated, and revised.
<ref-list>
<ref-list> contains a set of references (<ref>). It may or may not have a title.
<ref>
<ref> contains a reference of some kind. It will usually contain a single <element-citation>; however, complex References may contain multiple citations or a combination of text and citations.
See References for details on complex references.
<related-article>
Use this element's attributes to describe the related article's citation information. The related article must not be the article containing this tag. When using a DOI as the citation, tag the DOI in @xlink:href and @ext-link-type="doi". Element may be empty.
Source @article-typeSource @related-article-typeSource-to-Target Link TextTarget @article-typeTarget-to-Source Link Text
addendumaddended-articleSee the article [citation].[any]See the addendum [citation].
[any]addendumSee the addendum [citation].addendumSee the article [citation].
[any]alt-languageThis article is also available in [language]. See [article title]. (In language of the target article.)[any]This article is also available in [language]. See [article title]. (In language of the target article.)
article-commentarycommentary-articleSee the article [citation].[any except discussion, editorial, letter]See the commentary [citation].
[any]article-referenceSee the article [citation].
discussioncommentary-articleSee the article [citation].[any]See the discussion [citation].
editorialcommentary-articleSee the article [citation].[any]See the editorial [citation].
expression-of-concernobject-of-concernThis is an expression of concern about the following article: [citation][any]The editors have expressed concern about this article. See [citation].
lettercommentary-articleSee the article [citation].[any]See the letter [citation].
[any]companionSee [citation].[any]See [citation].
correctioncorrected-articleThis corrects the article [citation].[any]This article has been corrected. See [citation].
replyletterSee the letter [citation].letterSee the reply [citation].
retractionretracted-articleThis retracts the article [citation].[any]This article has been retracted. See [citation].
peer-reviewpeer-reviewed-articleSee the peer-reviewed article [citation].[any]See the peer-review [citation].
[any]peer-reviewSee the peer-review [citation].peer-reviewSee the peer-reviewed article [citation].

attributes:
  • related-article-type—Value describes the type of article being pointed to. Only use a value listed in the table above.(#REQUIRED)
  • ext-link-type—Required if @xlink:href is specified.
  • journal-id—Identifier for the journal containing the <related-article>
  • journal-id-type—Example: "nlm-ta" for PubMed title abbreviation. Required if @journal-id is specified.
  • id—(#REQUIRED)
  • page—Include only the first page of the target article.
  • xlink:href—May include target article's identifier (DOI, PubMed ID). If specified, @ext-link-type is required.
<related-object>
Use this element's attributes to identify the target object citation. The following objects must always exist together:
  • @source-id and @source-id-type
  • @document-id and @document-id-type
  • @object-id and @object-id-type
Specify the type of target object for the most specific unit. For example, if the <related-object> is a table in a chapter of a book, the table is the most specific unit so specify @object-type="table". If the <related-object> is a chapter of a book, the most specific unit is the chapter so the correct attribute is @document-type="chapter".
When specifying a journal article, the following attributes must be present:
  • @document-id
  • @document-id-type: Must be a DOI, a PubMed ID, or a PubMed Central ID
  • @document-type: Must be set to "article"
  • @id: XML ID of the <related-object> element
  • @link-type: Must be an approved value. See the approved values for @related-article-type described in <related-article>.
<season>
This is a text element. Values might include "Spring", "Fall-Winter", or month ranges like "Apr-Jun". Month ranges should be 3-letter abbreviations separated by a hyphen.
Do not include the year in <season>.
Also see Dates.
<sec>
All sections must contain <title>, <label>, or both. If it does not have either, do not tag it as a section.
<sig-block>
Used to capture signatures. If multiple signatures appear, capture in a single <sig-block>.
<styled-content>
Bookshelf does not guarantee that the display specified in the attributes will be implemented on the HTML rendering of the document and strongly discourages using this element.
<subject>
Defines the subjects of a book or chapter.
Do not include any <xref> within <subject>.
Do not include formatting elements unless necessary to convey emphasis. See Formatted Text.
<supplementary-material>
Include the filename and an appropriate lowercase file extension in the @xlink:href attribute value when tagging <media>/@xlink:href, <graphic>>/@xlink:href, or @xlink:href on <supplementary-material>.
<table>
Tables should be fully tagged, not included as images.

attributes:
  • frame—Specify as "hsides"
  • rules—Specify as "groups"
<table-wrap>

Contains all parts of a single table.


attributes:
  • position—Use "anchor" for an inline-table, including tables that are contained within another object (<fig>, <table>, <media>) Use "float" for all others.
<table-wrap-group>
See Display Object Groups for information on when to use this element.
<tex-math>
This element should not be used to set math unless it is supplied as an alternative representation of an expression. See Alternate Versions of a Single Object for details.
If <tex-math> is supplied as alternate tagging for an expression, make sure:
  • That each expression is a complete Lateχ document, including header.
  • That all characters are represented in Lateχ notation and not with Unicode™ characters.

attributes:
  • id—(#REQUIRED)
<title-group>
This holds the document <title>.
It also allows <subtitle>, <trans-title-group>, <alt-title>.
If there is a footnote to the title, put the <xref> (with @ref-type="fn") in the <article-title> or <subtitle> element, and set the <fn> in the <fn-group> in <back>.
<trans-abstract>
Used to tag the document <abstract> in a language different than that of the parent document.
Tag the <title> of the abstract, even if it is equivalent to "Abstract" in the alternate language.

attributes:
  • xml:lang—(#REQUIRED)
<trans-title>
@xml:lang should be included on parent <trans-title-group>, not <trans-title>.
<trans-title-group>
Only tag elements in a single language in the <trans-title-group>. To tag titles in multiple languages, use one <trans-title-group> per language.
Each element contained within the <trans-title-group> must have a corresponding element in the primary language (do not tag <trans-subtitle> if no <subtitle> exists).

attributes:
<volume>
Tag numeric volumes as an integer only. If Roman numerals are used, tag as the Roman numeral only. Do not include the word "volume" or any related abbreviation in the tag.
If the citation is part of a special issue with no specified volume (like "Supplement 2005"), tag "Suppl" in <volume> and "2005" in <year>.
If there is no volume number, do not tag at all.
<xref>
Used to references to objects within the book.
Do not tag multiple id values in @rid.
Tag lists of cross references by including one <xref> element for each referenced object.
The changes in education level demonstrate the changing attitudes. 1, 2, 5
<p>The changes in education level demonstrate the changing 
attitudes.<xref ref-type="bibr" rid="B1">1</xref>
<xref ref-type="bibr" rid="B2">2</xref>
<xref ref-type="bibr" rid="B5">5</xref></p>
Tag ranges of cross references by including an <xref> for the first item, an en-dash (–), and an <xref> for the last item. Bookshelf will display the range as tagged.
The changes in education level demonstrate the changing attitudes. 1–3
<p>The changes in education level demonstrate the changing attitudes.
<xref ref-type="bibr" rid="B1">1</xref>–<xref ref-type="bibr" 
   rid="B3">3</xref></p>
Set the "linked text" inside of the <xref>.
The @ref-type must match the target object in the XML, regardless of the object's label.
Correct:
<xref ref-type="table" rid="T1">Table 1<xref>
. . . 
<table-wrap id="T1"> . . . </table-wrap>
Incorrect:
<xref ref-type="table" rid="T1">Table 1<xref>
. . . 
<fig id="T1">
  <label>Table 1</label>
</fig>	

attributes:
  • ref-type—The type of object being referenced: "app", "author-notes", "bibr", "boxed-text", "disp-formula", "fig", "fn", "list", "sec", "supplementary-material", "table", "table-fn".(#REQUIRED)
  • rid—The @id of the referenced object.(#REQUIRED)
  • id—Do not use.
<year>
Must be 4-digit number.