The current TEI P5 Guidelines provide several mechanisms by means of which one item of lexical information can refer to another, e.g.

• <usg type="synonym">..</usg> for synonym references
• <cit type="translation"><quote>...</quote></cit> for translation equivalents in bilingual or translation dictionaries
• <oRef>, <pRef> for the resolution of “~" headword placeholders in quotations and other dictionary text
• <xr>, <ref> as a general cross-referencing mechanism
• <ptr>, http://www.tei-c.org/release/doc/tei-p5-doc/en/html/ref-ptr.html
• <link>, http://www.tei-c.org/release/doc/tei-p5-doc/en/html/ref-link.html
• <mentioned> in the etymology section
• <term> for mentions of technical terms

To unify lexical references, we propose to use <ref> as the general element for a lexical reference and to use <xr> as the enclosing element that groups information related to this reference. The reference may be internal to a dictionary or pointing to an external source, even when the actual target lexical object is not explicitly known. In the latter case, <ref> can be used without an explicit pointing attribute. Furthermore the actual intended target of the reference can be of various possible types, namely a full entry, but also a specific sense, form or morpheme within a given entry.

For all such usages, the following attributes may be used on <xr> and <ref>:

• @type should be a mandatory attribute on <xr> for a lexical reference. Its default value should be "lexical" and can be superseded (or complemented by means of @subtype). It should be an indication of the lexical relation between the headword of the entry and the object referred to
• ref/@type may be an indication of the target object category (entry, sense etc.)
• ref/@xml:lang is recommended when <ref> actually contains an explicit lexical form
• ref/@target should point to the actual lexical object being pointed at when applicable
• ref/@notation should indicate, like we currently do on <orth> or <pron>, the actual notation used for the explicit lexical form when provided

The simplest use of and according to the present best-practices guidelines would thus look like this: <xr type="lexical"><ref xml:lang="el">pneuma</ref></xr>.

value of @type	description	example
lexical	default (root of hierarchy)
cognate	link to cognate in other language	<entry>   <form type="lemma">voice</form>   <etym>      <xr type="cognate">          <ref target="" xml:lang="sa">वाच्</ref></xr>  </etym> </entry>
etymon	link to (possibly reconstructed) root form	<entry>   <form type="lemma">voice</form>   <etym>      <xr type="etymon">         <ref target="http:///indo-european.info/pokorny-etymological-dictionary/u%CC%AFek%CA%B7.htm" xml:lang="PIE">u̯ekʷ-</ref>      </xr>   </etym> </entry>
synonym, hyponym, hyperonym, antonym , meronym (etc)		<entry>   <form type="lemma">      <orth>dog</orth>   </form>   <sense>      <xr type="hyperonym">         <ref xml:lang="en" type="entry">mammal</ref>      </xr>   </sense> </entry>
translation	translation equivalent	<entry>   <form type="lemma">      <orth>horrify</orth>   </form>   <sense>      <xr type="translation">         <ref xml:lang="fr">horrifier</ref>      </xr>   </sense> </entry>
cf	Untyped cross-reference	<entry>   <form type="lemma">      <orth>borcht</orth>   </form>   <xr type="cf">      <lbl>Cf.</lbl>      <ref xml:lang="nl" target="#M012340">burcht</ref>   </xr> </entry>

Suggested values for ref/@target:

• # + id: reference to element by id inside current document
• URI reference
• xpath/xpointer expressions, using TEI xpointer schemes (http://www.tei-c.org/release/doc/tei-p5-doc/en/html/SA.html#SATS)

Translation Equivalents

With a pointer, specified in @target, to some dictionary containing the word referred to:

<entry>
  <form type="lemma">
     <orth>dog</orth>
  </form>
  <sense>
     <xr type="translation_equivalent">
        <ref xml:lang="fr" type="entry" target="http://www.cnrtl.fr/definition/chien">chien</ref>
     </xr>
  </sense>
</entry>

Without a concrete reference:

<entry>
  <form type="lemma">
     <orth>dog</orth>
  </form>
  <sense>
     <xr type="translation_equivalent">
        <ref xml:lang="fr" type="entry">chien</ref>
     </xr>
  </sense>
</entry>

A more complex example including quotations.

<entry>
  <form type="lemma">
     <orth>dog</orth>
  </form>
  <sense>
     <xr type="translation_equivalent">
        <lbl>Male or unknown gender</lbl>
        <ref xml:lang="fr" type="entry">chien</ref>
        <cit>
           <quote xml:lang="fr">
              Le matin j'ouvre au
              <xr type="headword_attestation">
                 <ref type="entry">chien</ref></xr>
              et je lui fais manger sa soupe. Le soir je lui siffle de venir
                  se coucher</quote>
           <bibl>RENARD, Poil de Carotte, 1894, p. 102.</bibl>
           <cit type="translation[ag]">
           <!-- included in the french cit, otherwise relation is lost -->
              <quote xml:lang="en">In the morning, I open the door for the
                        dog, and i ...</quote>
           </cit>
           <bibl>
              <!-- If the translation is from a published source, there
                        could be a bibl here as well -->
           </bibl>
        </cit>
     </xr>
     <xr type="translation_equivalent">
        <lbl>Female</lbl>
        <ref xml:lang="fr" type="entry">chienne</ref>
        <cit xml:lang="fr">
           <quote>6. Les fleuristes, murmura Lorilleux, toutes des
                         Marie-couche-toi-là.  Eh bien! Et moi? reprit la grande
                        veuve, les lèvres pincées. Vous êtes galant. Vous savez,
                        je ne suis pas une
              <xr type="the_type_formerly_known_as_oref">
                 <ref type="entry">chienne</ref></xr>
              , je ne me mets pas les pattes en l'air, quand on siffle!
           </quote>
           <bibl>ZOLA, L'Assommoir, 1877, p. 681.</bibl>
           <!-- possible translation -->
           <cit type="translation">…..</cit>
        </cit>
     </xr>
  </sense>
</entry>