20 Private Data

20.1 Introduction

SVG allows inclusion of elements from foreign namespaces anywhere with the SVG document tree. In general, the SVG user agent will ignore any unknown elements except to include them within the DOM. (The notable exception is described under Embedding Foreign Object Types.)

SVG's ability to include foreign namespaces can be used for the following purposes:

To illustrate, a business graphics authoring application might want to include some private data within an SVG document so that it could properly reassemble the chart (a pie chart in this case) upon reading it back in:

<?xml version="1.0" standalone="yes"?>
<svg width="4in" height="3in"
     xmlns = 'http://www.w3.org/Graphics/SVG/svg-19990706.dtd'>
    <myapp:piechart xmlns:myapp="http://mycompany/mapapp"
                    title="Sales by Region">
      <myapp:pieslice label="Northern Region" value="1.23"/>
      <myapp:pieslice label="Eastern Region" value="2.53"/>
      <myapp:pieslice label="Southern Region" value="3.89"/>
      <myapp:pieslice label="Western Region" value="2.04"/>
      <!-- Other private data goes here -->
  <desc>This chart includes private data in another namespace
  <!-- In here would be the actual graphics elements which
       draw the pie chart -->

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