If you get errors complaining of undefined entities like when
parsing xhtml it means you need to install the DTD for xhtml 1.0 or
Example of a doctype for xhtml 1.1:
You want to install the DTDs locally following the model in /etc/xml.
If you don’t libxml will fetch the DTD from www.w3.org each time you
parse a document. Needing to install these DTDs was not obvious to me
and should be part of the documentation. There a rpm for xhtml 1.0 -
“xhtml1-dtds-1.0-7”. I couldn’t find one for xhtml 1.1 so I downloaded
it piecemeal from w3.org.
Installing the DTD does not automatically turn on validation. If you
want to validate you need to turn it on:
XML::Parser::default_validity_checking = TRUE
XML::Parser::default_load_external_dtd controls the loading of the
‘external subset’ (the definition for the character entities like
&. It is defaulted to TRUE.
XML::Parser::default_load_external_dtd is broken. This fixes it.
RCS file: /var/cvs/xml-tools/libxml-ruby/ruby_xml_parser.c,v
retrieving revision 184.108.40.206
diff -r220.127.116.11 ruby_xml_parser.c
< if (xmlSubstituteEntitiesDefaultValue)
Sam’s patches for libxml are also needed: