THDL Toolbox > Places & Geography > THDL Gazetteer > Gazetteer DTD Decoded For Dummies > extptr Element
<!ELEMENT extptr EMPTY> <!ATTLIST extptr %a.common; entityref ENTITY #IMPLIED href CDATA #IMPLIED xpointer CDATA #IMPLIED>
extptr = External Pointer. An empty linking element which connects the gazetteer to an external (most often, binary) electronic object, such as an image. It is a semantic error not to have either an entityref or href attribute.
The href attribute is provided as a substitute for entityref's actual URI for those systems incapable of handling entityrefs.
The xpointer attribute is for specifying the target using CDATA, e.g. an XPath expression.