Roundtripping Alternate Content

Office Open XML defines a mechanism for the storage of content which is not defined by this Office Open XML Standard, for example extensions developed by future software applications which leverage the Open XML formats. This mechanism allows for the storage of a series of alternative representations of content, of which the consuming application should use the first alternative whose requirements are met.

example:

<ve:AlternateContent xmlns:ve="…">
  <ve:Choice Requires="colors" xmlns:colors="urn:randomTextColors">
    <w:p>
      <w:pPr>
        <colors:random colors:val="true" />
      </w:pPr>
      <w:r>
        <w:t>Random colors!</w:t>
      </w:r>
    </w:p>
  </ve:Choice>
  <ve:Fallback>
    <w:p>
      <w:r>
        <w:rPr>
          <w:color w:val="FF0000" />
        </w:rPr>
        <w:t>R</w:t>
      </w:r>
      <w:r>
        <w:rPr>
          <w:color w:val="00FF00" />
        </w:rPr>
        <w:t>a</w:t>
      </w:r>
      …
    </w:p>
  </ve:Fallback>
</ve:AlternateContent>

The <Choice> element that requires the new color extensions uses the <random> element in its namespace, and the <Fallback> element allows clients that do not support this namespace to see an appropriate alternative representation. ]

These alternate content blocks may occur at any location within a WordprocessingML document, and applications shall handle and process them appropriately (taking the appropriate choice).

However, WordprocessingML does not explicitly define a set of locations where applications shall attempt to store and roundtrip all non-taken choices whenever possible. This behavior is therefore application-defined.

example:

<ve:AlternateContent xmlns:ve="…">
  <ve:Choice Requires="colors" xmlns:colors="urn:randomTextColors">
    …
  </ve:Choice>
  <ve:Fallback>
    …
  </ve:Fallback>
</ve:AlternateContent>

The file would then appear as follows after the choice is processed:

<w:p>
  <w:r>
    <w:rPr>
      <w:color w:val="FF0000" />
    </w:rPr>
    <w:t>R</w:t>
  </w:r>
  <w:r>
    <w:rPr>
      <w:color w:val="00FF00" />
    </w:rPr>
    <w:t>a</w:t>
  </w:r>
  …
</w:p>

The state of the alternate choices (preserved or not) is dependent on the application hosting the file. Preserving the content involves storing each non-taken choice while the file is being edited, and writing out the file with an <AlternateContent> block when it is resaved. ]