<ptr>

<ptr> (pointer) defines a pointer to another location. 3.6 Simple Links and Cross-References 16.1 Links
Module core — 3 Elements Available in All TEI Documents
In addition to global attributes att.pointing (@target, @evaluate) att.typed (@type, @subtype) att.declaring (@decls)
cRef (canonical reference) specifies the destination of the pointer by supplying a canonical reference from a scheme defined in a refsDecl element in the TEI header
Status Optional
Datatype 1–∞ occurrences of 

<rng:ref name="data.word"/>
data.word
separated by whitespace
Values the value of cRef should be constructed so that when the algorithm for the resolution of canonical references (described in section 16.2.5 Canonical References) is applied to it the result is a valid URI reference to the intended target
Note
The refsDecl to use may be indicated with the decls attribute.
Currently these Guidelines only provide for a single canonical reference to be encoded on any given ptr element.
Used by
May contain Empty element
Declaration

<rng:element name="ptr">
 <rng:ref name="att.global.attributes"/>
 <rng:ref name="att.pointing.attributes"/>
 <rng:ref name="att.typed.attributes"/>
 <rng:ref name="att.declaring.attributes"/>
 <rng:optional>
  <rng:attribute name="cRef">
   <rng:list>
    <rng:ref name="data.word"/>
    <rng:zeroOrMore>
     <rng:ref name="data.word"/>
    </rng:zeroOrMore>
   </rng:list>
  </rng:attribute>
 </rng:optional>
 <rng:empty/>
</rng:element>
element ptr
{
   att.global.attributes,
   att.pointing.attributes,
   att.typed.attributes,
   att.declaring.attributes,
   attribute cRef { list { data.word, data.word* } }?,
   empty
}
Schematron

<sch:report test="@target and @cRef">Only one of the
attributes 'target' and 'cRef' may be supplied.</sch:report>
Example
<ptr target="#p143 #p144"/>
<ptr target="http://www.tei-c.org"/>