Prince processes well-formed XML 1.0 documents with full support for namespaces, internal and external entities, DTDs, character references and CDATA sections. Comments and processing instructions are ignored and do not affect the output.
Prince loads DTD files in order to resolve entity definitions and default attribute values. However, Prince does not perform validation upon input documents. If validation is a processing requirement, the use of an external validator is recommended.
Prince supports the
xml:lang attribute, which is used to
indicate the language of the document text. Elements can be selected by
language using the CSS
Prince supports the
xml:id attribute, which is used to give
elements a unique identifier. This identifier can be used when creating
links and cross-references; it also allows elements to be selected
using the CSS ID selector.
Prince does not support the
xml:base attribute, therefore
hyperlinks must be absolute URLs or relative to the document path.
Prince provides sensible default styling behaviour for several common XML vocabularies:
svgelements are treated as replaced elements, similar to
imgelements in XHTML, and their content is rendered in a rectangular space. No line breaks or page breaks are made within an
svgelement. (See Scalable Vector Graphics (SVG) for details of which elements are supported).
XML Inclusions (XInclude) provides a method of including content from other files into an XML document. When Prince processes the XML document, the inclusions are resolved and the included content is treated as if it had been in the original document all along.
The core of XInclude is a single element,
<include href="..."/>, which
specifies the inclusion of the file referenced by the
attribute. The element is in the XInclude namespace,
http://www.w3.org/2001/XInclude, which must be declared either
on the element itself or one of its ancestor elements.
Please note that XInclude is disabled by default, and can be enabled with the
--xinclude command-line option. (See Input Options.)
Here is an example of a book written in XHTML in which each chapter has been placed in a separate XML document for convenient editing and then included in the main document using XInclude:
<html xmlns:xi="http://www.w3.org/2001/XInclude"> <head> <title>Book Title</title> </head> <body> <xi:include href="chap1.xml"/> <xi:include href="chap2.xml"/> <xi:include href="chap3.xml"/> </body> </html>
(Note that the XInclude namespace was defined on the root element and bound
xi prefix to save space by avoiding the need to declare the
namespace on every inclusion).
XInclude can also be used to include text files into XML documents:
<xi:include href="file.txt" parse="text"/>
This is a convenient way of including files containing arbitrary non-XML text, such as emails, database reports or program source code. It also allows the inclusion of external XML content as "unparsed text", as if all the markup had been explicitly escaped with character entities or placed in a CDATA section.
It is possible to specify fallback content that should be used if an included file cannot be loaded. The fallback content can be arbitrary XML and may even contain additional inclusions.
<xi:include href="report.html"> <xi:fallback> <p>No report is available</p> </xi:fallback> </xi:include>
report.html file cannot be loaded then the paragraph
saying "No report is available" will be included in the document instead.